Powerboats are nice! They have lots of space in them and are typically made to feel plush and lavish. Aside from houseboats, powerboats take as much advantage of the beam available to provide a large interior living space.
The most common type of liveaboard powerboat we have come across in marinas has been the motoryacht. Motoryachts are simply huge wide boats with as many rooms as they could cram into them. The bows of these boats will flare out quickly as they develop their full beam very far forward and this full beam will extend all the way back to the transom, usually ending in a very large owners cabin. These boats are expensive to operate, but if all you do is stay tied up in a marina, they only cost the slip fees.
Motoryachts will tend to have a stateroom aft, also known as the "owners cabin", a stateroom forward; and if large enough, a third stateroom midship. They will usually have at least two heads (boat bathrooms), one forward and one aft. The galley will be located near the salon near the middle of the boat, where the large windows will let in plenty of natural light to make the interior bright and airy. In the winter, these huge windows will be a huge source of heat loss, which can be easily remedied by shrink wrapping the boat. While motoryachts will have plenty of closet space, most liveaboards will convert the forward stateroom into a storage room and closet for their off-season clothes. These boats are tend to be considered "floating condominiums" by their owners, as they never leave the slip.
Sport fisherman boats are the next most common motor boat we come across being used as a liveaboard. They are very similar to a motoryacht in hull size, but the entire aft cabin and deck is lost to give way for a massive cockpit. These cockpits are nice during the warm months, when these owners will typically entertain a party in this open area. Cockpits are a good place to host an event because if someone spills a drink, it can be easily washed away with a hose. There is no concern of staining carpet or hurting interior grade wood soles. Cockpits are designed to pull bleeding fish into and be washed out later. In the winter, most sport fisherman liveaboards will set up a frame in the cockpit, allowing the shrink wrap to make an additional room that would otherwise be lost in the cold months. Of the liveaboards I know personally, the ones who live on sport fisherman boats tend go out for the weekend more often than those who live in motoryachts. I also find that those in sport fishermans will have less house type items, such as large TVs standing on their unsupported base in exchange for a bulkhead mounted TV that will not fall over when they bounce around in the Chesapeake chop.
Express cruisers are much sleeker looking than a motoryacht, and tend to be very plush! They typically have a full galley inside and a small galley in the cockpit, where drinks and snacks can be stored and then presented to guests. Inside, these boats tend to be smaller than a motoryacht. Motoryachts are massive blocks on the water, offering loads of interior volume with subtle features to make them hydrodynamic, where express cruisers are very sleek, sacrificing interior volume. The massive engines also tend to be in the back of the boat where the owners cabin would be on a motoryacht, meaning one less cabin inside. Even at very long lengths, these boats do not offer much interior space. They tend to be setup on one level, where a comparable motoryacht will have two levels, giving you twice the interior space. The sleek lines and massive engines of an express cruiser make them notably faster than a motoryacht or sport fisherman. One of our neighbors is very pleased that his express cruiser can do nearly 30 knots!
On the other end of the powerboat spectrum are trawlers. Trawlers have less interior volume than other motoryachts, but are very fuel efficient. Trawlers are based off of the fishing trawler style of boat, moving slow and steady through the water with its high bow and transom. Trawlers are practically sailboats with a tiny mast and a large motor. They do not plane and are limited to their hull speed, but this also means that they do not consume much fuel. Most of my friends with trawlers consume around two gallons per hour. While most people with trawlers are retired sailors, some of them are actually first time boaters who decided they like the look of these boats. Thanks to their low fuel consumption, these powerboats are very economical to run and the owners will take them on very long distance voyages. Most of the people who live on trawlers in the marina are snowbirds, spending the summers up North and the winters in Florida. They make the trek down the East coast in the ICW every year in these boats, greatly demonstrating the long distance capability of trawlers.
Trawlers tend to have a more traditional interior, with varnished wood on every surface instead of soft fabrics and coverings. There are also two common styles of trawlers, tri-cabin and sedan. The big difference is a tri-cabin has an aft stateroom under the dinghy platform where the sedan has a larger salon with no aft stateroom. Basically, two staterooms for the tri-cabin versus one stateroom for the sedan.
The sedan trawler has a much larger salon with a lot of natural light, but you are forced to sleep in the bow and there is no additional stateroom for guests. The tri-cabin has three smaller rooms, a central salon with steps forward that lead down to the forward stateroom and steps aft that lead to the aft stateroom. The engine is under the raised floor of the salon, allowing plenty of access for maintenance and engine repairs on both styles of trawlers. They tend to only have one engine, but some of the larger models have two motors which gives you added maneuverability as well as added fuel consumption. Most trawler owners are retired sailors as they are well versed in maneuvering single screw vessels and are accustomed to the slow voyaging speeds of a displacement hull.
If you are thinking of living aboard a powerboat, consider what you want from your boat and what you want to do with your boat, then try to find one that you also think has pretty design lines. If you want a dockside condo that will never leave the slip or fuel costs do not concern you, consider a voluminous motoryacht or sport fisherman. If you are more fuel conscious and also want to travel great distances, consider looking at trawlers. Lastly, if you want to go really fast and are willing to sacrifice interior space, you would greatly enjoy an express cruiser.