Have you thought about a kids club for Hannah? For my DH's birthday, we dropped off our son at the Neverland Club, rode the monorail over for a relaxing dinner at the California Grill, took the monorail back over (front car, of course) and picked up our DS. My DS LOVED his time at the Club, and we enjoyed a peaceful dinner. (Note: we stayed offsite and had no problems getting our son into this kids club. We parked our car at the Poly, after telling the guard what our plans were. No problem leaving the car for the evening).
Another time, my SIL got sick at the last minute, and we took our son with us to Narcoussees (?sp) to celebrate my Birthday. The staff there was great. Brought my DS a special drink with an umbrella. We had a window seat and were able to see the fireworks. Of course, it was pretty expensive.
Another idea is to get a lagoon side table at the Rose and Crown for about 7. You could have a lovely dinner and catch Illuminations.
And, there's always the character meals. I'm not sure it that would be the first choice for a thirtysomething special birthday, though.
Good luck!