Hi Brandy,
The main differance between Sheraton and Dreams is that Dreas is an AI resort, so if your having a large wedding in Cabo, you'll end up probably saving money having it there.
I'm having a small wedding, (10 people max) and were getting married at the Sheraton. They don't have an onsite WC to do a legal wedding in cabo (she's more of an event planner, not a WC) but Irma at the Sheraton is great to work with and will help you in booking your reservations for dinner, ceremony or whatever. I also hired a WC (Maye C.) who is actually handling most of the details of the wedding.
Getting Married on the beach at the Sheraton is actually pretty reasonable, it's only costing us $330.00 and that includes chairs, chair covers, tiki torches and a table for signing of the license. Then were having dinner at De Cortez, which is located right next to the beach.
I wanted a romantic, intimiate setting for our wedding day. The second I stepped foot on the Sheraton grounds I knew it was the place I wanted to have our wedding. If someone is interested in a church or garden wedding they also have both locations onsite as well. Both are very pretty (do a search on Sheraton and there is a post with pictures of the resort)
If you have specific questions feel free to ask, and I'll try to answer.