Do you & your Mom absolutely not want to go to UO? I always recommend anyone visiting UO to stay onsite. Not only for the FOTL, but also for the relaxing vacation it provides. Yes, I too was surprised the 1st time I realized a theme park vacation could be relaxing.

The UO onsite experience is like none other. You & your Mom could visit the parks for a little while, do some shopping, then walk or take a short boat ride back to the hotel. Rent a cabana for a day, & spend some quality time lounging by the pool & chatting with your Mom. When it's time for dinner, enjoy a nice meal in your or one of the other resorts, or at CW. Once again, it's only short walk or boat ride away. Do this at the end of your trip, & go home relaxed.
If this doesn't sound appealing to you, only your family knows if it would be better for them to stay at UO, while you're at WDW. It's not something my family would do, but that's just a personal choice. Actually, I'm a coward w/o my hubby.
To help them decide, I can tell you that staying onsite will give them FOTL on rides as many times as they want to ride. The Express Pass only gives you FOTL privileges one time per ride. A 16 yo. is probably going to want to ride the thrill rides multiple times.
As far as hotels go, if you & your Mom decide to go also, Portofino Bay Hotel provides more of an escape from the parks. It's very nice & caters more to adults, IMO. However, it's further from the parks than the other 2 resorts. We took the boat to & from PBH, but some people walk. For a 16 yo. boy, Hard Rock Hotel is the place to be.

It's also less than a 10 min. walk to the parks & CW.
Happy planning!!!
