I submit that enjoyment is the whole point of owning a boat. Enjoyment under sail or power, it does not matter. Enjoyment of your time aboard is the goal; and that includes your boat's interior. I spend a lot of time on my boat and I am particular about her. An interior should be clean, comfortable and attractive. Here are some ideas that I have developed to help assure interior comfort.
A top priority must be the prevention of deck, hatch and port leaks. Any boat that has such leaks is prone to damp bunks plus mildew and odours. You must do whatever it takes to address such leaks. Sometimes that involves simply re-bedding fittings; or it may require port or hatch replacement. If the source of your leaks baffles you, seek professional advice. There may be inexpensive options like the replacement of seals or lights in existing hatches and ports. This is where buying quality fittings in the first place pays-off. I have Perko bronze ports made in the '60s for which I can still purchase gaskets.
The provision of adequate ventilation is a necessity as well. Ventilators that allow air into the interior, but not rain and spray, come in a variety of types . The 'Dorade' vent, designed by Sparkman & Stephens and introduced on the famous yawl of that name was among the first; but there are now self-contained ones that are low-profile and work well. A good chandler can help you to decide what is best for your boat. Don't underestimate the importance of simply opening hatches and ports when the weather allows and letting the breeze blow through. I have had fabric hatch covers made with screens that allow hatches to remain open over a wide range of conditions.
In our climate I believe that a good source of heat is essential to the enjoyment of one's boat. If you spend any amount of time aboard, cool and damp weather is going to be experienced. Much has been written on heating alternatives. I favour systems that allow independence from shore-power, the noise of generators and that do not require constant attention. I have a diesel engine and I carry lots of fuel so a diesel- fired heating system is my choice. These come in various forms. Depending on the size of the boat and its lay-out a diesel-fired hot air furnace might be best. I have a diesel fired Dickinson range with a 'pot-burner'. These come in both heater and cook-stove versions. I have the latter but it is a compromise as a second stove is needed in warm weather; but when it is running and the boat is warm and dry, and the oven is hot, it is wonderful to cook in.
If your boat is equipped with propane for cooking, then a propane heater may make sense. It is important that the heater be vented to draw-off the hydrocarbons otherwise condensation will be a problem. For the traditionalist, wood and coal stoves are available. On the other end of the spectrum is obtaining heat by means of reversing the cycle of air-conditioning units. A/C is an inefficient way to heat a boat and away from the dock you will need to run a generator. Careful selection based upon your needs and the nature of your boat will add greatly to your enjoyment of her. Being cold and wet is no fun at all.
Comfort aboard also requires proper storage of deck gear. Sharing accommodations with wet sails or grimy fenders isn't much fun either. This means that planning and adequate deck and cockpit stowage is important. In other words a comfortable interior requires a well-planned exterior. Smart interior storage is important too. This starts at the design stage. Adequate, secure galley storage for food and cooking gear is a start, followed by clothing and personal gear. One of my complaints about some modern designs is that living space is maximized at the expense of storage space. Storage capacity should match bunk capacity. This is where the reality of living aboard often collides with boat-show staging.
When it comes to interior appointments, we all have our preferences. I prefer fabric cushions on the sleeping bunks. Larger vessels may have the luxury of fitted marine spring mattresses and matching bedding. This is ideal if the boat is large enough that sleeping and living spaces are separate. Matching the appointments to your taste and lifestyle (including kids & dogs) is the key. Fretting over the preservation of an expensive though unsuitable interior will not add to your enjoyment of boating. Cabin sole coverings should be matched to your needs too. Carpet is non-slip and it deadens engine noise, but it may be wholly unsuitable in areas where engine access and maintenance is necessary. It goes without saying that carpet in the head and galley is asking for unspeakable stains and smells. Under the best of conditions carpet is tough to keep dry and clean. Teak soles are traditional and are now most often rendered by means of veneer panels. Highly varnished wood soles are slippery and subject to damage, particularly in the galley where things get dropped. It's all a compromise. Sometimes simple is best. I have a plywood sole on my ketch which I have over-laid with solid teak in the galley; the rest is painted and highlighted with non-skid patches of Tread Master. It is tidy, non-slip and durable and I can take a mop to it. In cool weather, I have a fitted, bound carpet for the main cabin that is easily removed and stowed.
Part of the secret of enjoying your boat is maintaining her so that she is clean, dry and comfortable and appointing her to meet your needs and tastes. This is an evolutionary process that comes from use and experience plus attention to detail. Your needs change and so should your boat. A bonus is that maintaining and upgrading your boat helps to maintain your investment in her too. An experienced yacht broker can help you to prioritize projects and offer advice on the products and services that are available in your area.