Did I do the right thing?

[sndral]

My stepdad really wants a deluxe because he wants a balcony to sit, have a drink, and relax.

Be aware that you may end up in rooms w/out balconies @ the Poly - particularly if you have requested connecting rooms as well, as they'll first fill the connecting request and the balcony request will be secondary (@ least that's what I was told when I got no balcony connected rooms.) I think it's a little under a third of the rooms don't have balconies.
If I were trying to persuade your mom that the Poly was the best choice, I think I'd focus on how much more bang for your buck you are getting by being on the MK monorail and being able to walk to the Epcot monorail, you save so much time w/ no bus travel to 2 parks especially w/ children who may need a mid day break.

 

[maryj11]

I have stayed at several Disney resorts and the Poly is my favorite. The transportation alone is a big plus. Oh and watching the fireworks and the water parade on the beach at night is one of my favorite things there. Make sure you make reservations for Ohana ! I would do it now because they are really hard to get. The dinner and character breakfast are really nice. Another reason I like the Poly is it is not a large resort with not much walking I would maybe tell your mom before you go so there wont be any hard feelings.

 

[AliceIn]

I agree that you should at least tell your mother ahead of time. I would not want to do Disney with an angry or resentful relative.

I would tell her also. Lying about the money spent (on your stepdad's part), could cause a major problem for your mother. My husband is not that great at budgeting, and this is something he'd do because he's clueless about bills, budgets, and how many other bills might be coming up. I am fine with spluring sometimes, but if I've set a budget and he went behind my back and spent when I'd specifically said no, the vacation would be ruined. Financial decisions are shared - and there is a big cost difference between a moderate and a deluxe vacation. 'Fess up now. You and your kids can always stay at the Poly if that is what you can afford. If your mother is ok with the extra expense, they can stay there also. If not, they can always move back to POR on their own.