I inherited my first motorhome,a 21' class c that was my dad's project.
We kept that for a year or so and made notes of what we wanted and needed.
The main thing at that time was a place to sit when the kids are still sleeping in the dinette bed. That MH did not have a grey water tank either.
We upgraded to a 26 foot C with two chairs, a couch/bed as well as the dinette bed.
After ten years of that we decided we didn't want a MH any longer.
The next RV we purchased had to have all the things the 26' c had, plus a walk around bed.We ended up with a 26' travel trailer.
I don't know that I would have done anything differently had I bought my first motorhome rather than inherited it. I think I still would have started out with something small and cheap and figured out what I really wanted or needed.