Really look at how much room you want. I have a 21ft class C. It is great for ease of setup - just back in and level. It's big enough to have room for my needs. It has the cabover bed. I skipped the tele, microwave, etc, so my electrical needs are the least of my concerns. I can go well over 10 days without an issue. My limit is based on water. I have a 40 gallon fresh water tank that lasts 12 days with no showers but no major conservation in other needs. My 20 gallon grey and black tanks fill equally, so it's pretty perfect.
Due to the height and width, it is difficult to park in major cities, but I have no problem elsewhere. So, no need for a toad. By always putting things away after use, it is easy to drive off for a day trip and return.
A friend has a Toyota Sundrader. It is smaller than mine in all dimensions, but still has the same basic amenities. She can drive most anywhere and can easily park in cities. Again, it has a cabover bed.
A 24ft class C is the smallest you'll see with a dedicated bed below. It will likely be a corner bed. 26ft and up will more likely have a dedicated bed with access on both sides. GVWR will be your catch - many are limited. You really want to determine your weight needs first.
Gas mileage is going to be 7-10mpg regardless of size, etc. So you can figure out travel time on one tank from that.
A smaller class A might be a good option. Something under 32ft. Your wife might find driving it OK. And it is likely to have a greater GVWR.
I suggest you start visiting dealers and sitting in various sizes and classes. Look at the weights and tank capacities and make notes. Then you can start to determine which have what you want in a comfortable layout.