It makes sense that you would like non-folders. We don't RV, but went for cruisers for the upright riding position and comfort for recreational riding and commuting. My husband and I use our bikes pretty heavily (1500 miles in 4 months, most of that clustered in a 2 month period), so riding comfort was a big factor.
My bike has bigger tires, and works fine on firm/crushed gravel surfaces. My 75" long cruiser is great for city, suburban, and well-kept bike trail riding. The fatter (but not "fat") tires are great for safety around pavement grooves and such which are treacherous for the skinny tires that road bikes use. Weight really isn't an issue for city and suburban riding. Occasionally I need to lift the rear of the bike to pivot at a crosswalk or something.
I don't like how my bike handles in deeper or larger gravel, though, or on walking trails that are rooty or have tight turns or are not really designed for cycling. For more variable trail conditions, curves, bumps, roots, softer surfaces, etc., I think a more nimble bike would be better. It isn't just tire width that's important for bumpier/curvier/softer trails, but also length, and for less bike-friendly trails, the upright cruiser positioning and swept-back handlebars that make it so great for established roads and bike paths make for lousy handling over roots, bumps, quickly-changing surface conditions and around curves. We have wooded parks near us with walking trails that bikes are permitted on, but I had to walk my bike in some areas--just couldn't maneuver safely.
Happy shopping!