We kept it simple and affordable as well with our 31' Class C. No slides, didn't need the weight or mechanical issues that can come from them... a slide is nice and all, but we're outside most of the time. We have smaller holding tanks, around 40 gallons I believe, again weight factor.. and we're conservative.
We tossed around the idea of a conventional trailer or toy-hauler, but neither of our vehicles will comfortably tow something that large. We're at a 3500lb tow capacity, and a trailer would be borderline heavy, and loaded it would probably be over weight. There are light trailers, but they're generally more money... and we just didn't want to chance it with our vehicles. So we opted for the Class C, with a powerful Ford V-10. Probably the best power plant for a large RV. Really about the only one other then the Chevy Workhorse.. which isn't highly rated. The Ford V-10 does it's job very well, and is quiet smooth power. We stayed well away from anything diesel... servicing those, and getting them worked on can be challenging, whereas the Ford V-10 can be serviced by many places...and parts are readily available. We probably won't need parts for a long time though.
It would have cost us much more if we went for a trailer, as we would have needed to replace one of our current vehicles with a tow vehicle. If you already have a tow vehicle though you're half way there, and a nice used trailer can be had for a very reasonable price. If you have a vehicle to tow, a nice trailer can be had for probably $10k or less if you shop it. Toy-hauler styles are a bit more expensive, but still not bad. Another factor for our Class C is it tows our plane/toy trailer... or whatever we want. We couldn't carry my planes with a conventional trailer, my planes are too big to fit through any RV door. If you fly smaller planes, the sky's the limit though.
So there' was much consideration before we bought this recent RV. Hopefully it will last us for years. We did 7,000 miles last year, and are about to take our first trip this year into Death Valley... after that the IMAC season starts for us here in Central Cali, and we can get out and fly those events. They've already started in Az, and So Cal, and we have to catch up to them.