Denny's is not so bad---
Now a chinese restaurant on Christmas Day b/c a wild pack of dogs came in and ate all the Turkey--now that isn't so great. (Christmas Story!!

)
I believe they should have a plated turkey dinner--and I am partial to diner turkey dishes myself.
The holidays are what you and your family make of it.
It isn't a place or a specific location. It's the people you are with and the feelings they create.
You and your mom are not up to cooking--but you will have your holiday dinner together.
Often there are other restaurants that offer Thanksgiving Dinner and hotels often have a buffet. So if you want to check around to see if something will be "closer to home style"--go for it!
But I wouldn't feel bad that dinner isn't in a house.
ETA: You might check if there is a Cracker Barrell near you. They make a really good thanksgiivng dish, or even thanksgiving to go.
Dinner is only $8.99 and includes pumpkin pie and beverage and they are open all day, regular hours (dinner served beginning at 11am):
http://www.crackerbarrel.com/menu.cfm?doc_id=1281
In restaurant meal:
Dinner to go: $49.99, requires 48 hours notice.
There is at least 2 in the MElbourne Area--up at I-95 and Wickham in Viera and the other is on Palm Bay Road (I think near....BJ's I think).
And--stuffing AND pumpkin pie are on the menu.
Very homey atmosphere--one of our favorite places to eat away from home.