My current wife is another of those that is not fully into the whole RV travel thing yet, since buying my current coach (28 ft class A) about 2 years ago, she has only travelled with me about 1/3 of the time, the rest has either been solo or with my college age son from my first marriage.
In my travels have have met number of solo RV'ers both men and women, and even from my own travels I find a 28 ft coach to be more than spacious enough, if I were on my own I could probably be happy with a 22-24 class B / B+, though I might miss the cargo carrying capacity of my current coach.
Picking the right type of RV is all about knowing how you will use it, do you want a trailer of some type or a motorhome. Lots of times a trailer makes a certain economic sense, particularly if you already have a vehicle to tow it with. Personally I like the ease of motorhome travel, pull into a roadside rest area, get out of the drivers seat walk back to the kitchen fix a sandwich, eat lunch, prop my feet up for a bit, watch tv, and go back to the drivers seat and hit the road for another couple of hours without ever stepping outside.
One word of caution don't listen to salesman when it comes to towing capacity, they will gladly sell you a 35 ft travel trailer and tell you that you can tow it with a mini-cooper, as long as it had enough power to pull the trailer off the sales lot.
p.s. if you know you will be travelling solo, take this into consideration when looking at floor plans, and general RV layout. Earlier this year I did a 2 week solo trip and on about day 9 or 10 I realized I had only sat in 3 of the 7 available seating positions on that trip (sofa, drivers seat, and rear seat at the kitchen table, the rest were a complete waste of space for me when travelling solo, two weeks ago my wife was with me on a 10 day trip, and on this trip all 7 available seating positions were used by one or both of us nearly daily.