A couple who did a good job of describing their process, and the good/ bad since are
RV-DreamsJust one piece of advice - make sure the wife is very happy with the kitchen area, and she should be happy with the rest of the layout also.
You'd hate to get into a situation where you have to give up one - the wife or the RV.
Expensive to replace either.
But also be aware, very few folks buy the perfect RV the first time. It takes some time living in them to realize what does/ does not work. Sometimes a cheaper used or smaller rig might be best, planning to replace it in three or four years.
Heated holding tanks/ underbelly are pretty standard on non-basic 5th wheels. Generator - depends upon where you will be camping.
Going from a TT to a 5er changes where you can camp. Know a couple folks who went to a TT because their 5er was too tall to fit under trees on many western states forest service and NPS campgrounds. Not just in campsites, but the roads in the campground.
A TT is 11 to 11 1/2 feet high. A 5er is 13 to 13 1/2 feet high. Since you mentioned a generator, I'm guessing you are talking about boondocking quite a bit.
The RV market is changing. One major well respected MFR now equips their models with an induction cooktop and a four door Propane/Electric fridge. I guess they assume everyone who wants the boondocking fridge will be cooking outside.
If you are wanting a washer/dryer - you might not be talking about boondocking. Either a generator or a W/D will add a good bit of weight. Probably don't need both, but your requirements are your own.