Arrive the Friday night before Thanksgiving. The crowds don't increase alot until Wednesday. We've been to WDW during Thanksgiving for years and we find this to be true every year. I'd subscribe to Tour Guide Mike-it's about 20 bucks and well worth it if you don't want to spend your time waiting in lines.
We usually switch to a Universal onsite hotel on Wednesday because of the front of the line access-5 minute wait tops.
This is our plan and we've found it works really well.