^^ Ok but on an ideal day at Thorpe, which is certainly achievable throughout the year, you'd have finished the park by lunchtime, sometimes including re-rides. Not many of the rides are particularly re-rideable (I'd limit it to the 2 B&Ms and Stealth), and none are good enough to warrant queuing for hours or coming back a second day.
Alton is big enough, nice enough to be in and with enough to do (including re-riding one of the world's best coasters) that it could fairly easily warrant two days. I really don't think Thorpe does. So, if you did just go for one day, I don't understand why you'd spend a night in one of the UK's smallest rooms in a useless location when there are a myriad of surrounding accommodations with bigger rooms, better prices and easier-to-access locations.