It is not recommended to ride two up for the first year on a bike.
Trust me when I say it adds a layer of difficulty more than you think it should. Even once you are a good rider, it is usually recommended that you have a good thousand miles on that particular bike before you ride two up. Obviously, communication skills, and your wife’s ability as a pillion (since riding as a passenger is a skill, it is not totally passive like in a car – they have to turn with you) will affect that time.
For your first year, plan on a riding only by yourself, except maybe some toodling around in a parking lot. First time I had my gf on the back of a bike I took every single corner waaay too wide (or at a complete crawl). Had we been on a road with the potential for on coming traffic, things could have gone very badly.
You’ll actually find that if distance trips are your intention, cruisers are not the best way to do it. They sit more weight on your tailbone, not your sitsbones. There is a reason touring bikes sit more upright and “standard” than cruisers.
All that said, if a cruiser is what you want, and two up is something you want to aspire to (if not do right away), I’d consider a 600/650cc cruiser.
The bike I rode 2up with my gf on was a Shadow VLX 600. It was very smooth, and pulled cleanly even with a passenger. It was no rocket, but it had enough torque for the two of us (combined weight about 350lbs).
As a learning bike, it is fairly heavy during slow speed turns. If you can throw a rebel around without issue, go for it. If you find the really slow speed stuff reasonably difficult in the MSF (and most people do). I would go with a lighter bike for the first season. Any of the 250 cruisers, or maybe the Savage/S40.
I mention the S40 because it has similar weight and dimensions to the 250s but it has a 650 single cylinder engine, so it should have enough torque for two up. However I have not ridden one, so take that with a grain of salt. Also it is a fairly small bike (being of similar size to the 250s), so it might be cramped if your a tall guy.
If you are looking at a Ninja250, don’t worry about its acceleration. Even two up it should out accelerate most small (<700cc) cruisers.
Anyways, those are my two cents, I hope they help.
Ride safe, and have fun.