We have been to the Swan, with the gov't discount. We have also stayed at WL in the past, as other WDW resorts. We, like you, stayed at WL before we went to the Swan. And although I am sure you will agree that WL rocks, I really believe you will love the Swan too. Here's my top ten:
1. Pretty darn inexpensive (with the teach/gov't discount you get the most economical room in the EPCOT resort area possible, and it's a deluxe!)
2. Beautiful, renovated rooms with "heavenly beds"
3. The Boardwalk (fun nightlife and excellent restaurants)
4. Pastries for breakfast at the Boardwalk Bakery or Krispy Kreme's at Tubbi's in the Dolphin (yum)
5. The Health Club (MASSAGE!!!)
6. Beautiful walking trails along the EPCOT resort loop
7. You can walk to EPCOT!
8. A serene quiet pool, in addition to the large meandering pool that the Swan and Dolphon share.
9. Good service (we had wonderful and attentive service when we stayed here)
10. Mini-golf (it's a fun way to spend an evening at the resort)
We did become Starwood members in advance of our Swan stay, and we did receive an unsolicited upgrade at checkin, which was an unexpected but welcome surprise. The Swan and WL are so very different from each other, but each is unique and has much to offer in my book. I hope you enjoy the Swan as much as we did!