If you are a points owner, you can book even a single day. For example, I went to Bonnet Creek in September for my birthday, and booked 4 nights. Just be aware: even though the salesweasels will tell you how wonderful it is to take multiple weekend or short vacations, EVERY TIME you book a vacation, whether for 1 day or 1 month, you are charged both a "transaction fee" and "housekeeping points." You are charged a weeks housekeeping points even if you stay only 1 day.
Ditto what was said above. Unlike DVC, with Wyndham you have to watch your transaction fees and housekeeping credits for short trips. And for higher/peak season travel, Wyndham has some rules about check-in days (like needing to be a Friday, Saturday, or Sunday or for so many days).
Something I really like with Wyndham (since I travel off season) is that they sometimes reduce the points required when you get within about two months of check-in. Here's an online snapshot of some discounts that Wyndham offered last January and February for Bonnet Creek (this was in December):
Check-In Nights Unit Type Details Points Discount
Points
JANUARY
01/08/2010 3 1 Bedroom Deluxe 66,000 49,500
01/08/2010 3 1 Bedroom Deluxe 66,000 49,500
Click to see details.
01/08/2010 3 2 Bedroom Deluxe 98,600 73,950
01/08/2010 3 2 Bedroom Deluxe 98,600 73,950
01/08/2010 3 2 Bedroom Deluxe 98,600 77,750
Note: Transaction combines two reservations and may require a room change.
This one is weekday check in:
02/07/2010 3 1 Bedroom Deluxe 45,000 36,000
02/07/2010 3 1 Bedroom Deluxe 45,000 36,000
02/07/2010 3 2 Bedroom Deluxe 67,800 54,240
02/07/2010 3 2 Bedroom Deluxe 67,800 54,240
02/07/2010 3 2 Bedroom Deluxe 67,800 54,240
02/07/2010 3 2 Bedroom Deluxe 67,800 54,240
02/07/2010 3 3 Bedroom 84,000 67,200