There are advantages and disadvantages of motorhomes and 5th wheels.
With a motorhome, you will usually have a vehicle aka a towed or known as a toad. This will require maintenance, insurance, etc for two engines. The diesel pushers are the powerful ones that will get you up and down the mountains. The advantage you will be able to disconnect the small vehicle and tour around.
With a 5th wheel, you will have much more living space and storage space, but you will need a very large, expensive truck. Diesel will be required and that will be your touring vehicle as well as the transporter of your RV. The other advantage is that the cost to maintain the truck will be cheaper than maintaining a motorhome, but will be more expensive to drive to tour around.
Different people have different needs. Join online groups to explore the best and the worst of each option. Are you buying new or used? Both will depreciate, 5th wheels are more difficult to back into the campground sites. There are books to help you pick which one is best for you and which brand of that type is the highest quality. Both are books are written by Randall Eaton. We started out wanting a travel trailer but ended up wanted and buying a 5th wheel after reading his book. There are ratings for the brands and include years past to give you information on used units.
Many people have romantic ideas about how fun and exciting life is going to be on the road. You will have good days and bad days just like life before retirement. Allow each other times to be apart and to do things together. RVing is more expensive than most people think and plan for. Campground fees can get very expensive and RV require regular maintenance. You can PM me if you have more questions.
The only decent motor home is the old 76 GMC 26 ft unit. Way before it’t time. 10-12 mpg. Computer controlled leveling system so if you have a side wind it levels itself. Drives better than most cars. You don’t feel like you driving a bus.