Okay, I found our old Plat. Plan brochure - the spa treatments included in '04 were: 40 min. manicure, 20 min. aromatherapy bath, 25 min. soothing tired legs treatment, 25 min. eye and neck treatment, 25 min. paraffin hand and foot treatment, 25 min. sea salt body polish, or 25 min. Swedish massage. If you go to relaxedyet.com there's more detailed info. I don't know how much the options will change for '06, but at least it gives you an idea
Also, it really is 1 treatment per guest - if you decide not to use your treatment, another person in your party can't use it...
The Swedish massage was short, but perfect for us - neither DH or I had every had a massage, and 25 min. didn't sound too scary

We were also glad to use the couple's room.
As far as splitting your resort - I would book 1 night in between the 2 packages room-only - your package and meals, etc. will last until midnight of the day you check out. The next morning you can re-check-in and your package will start all over again. I don't know how much $$$ this will save you - but otherwise you'll be paying for 2x for the meals and park tickets, etc. I guess it depends on how much of a hassle it will be for you. The way we did it was 7 nights POR Silver, 1 night POR room-only, 3 nights Poly, 1 night POP (checked-out at 6:30 am) - so for our entire stay we had park tickets, and some form of meals included without paying double for certain features.
HTH
