Well, I'm partial to Orient Beach. Did you see the recent thread where BellaClaire offers some great advice:

http://www.fodors.com/community/caribbean-islands/need-advise-for-st-maarten-in-october-2012.cfm

Dawn Beach is nice for a day. Pinel Island is a short ferry ride (4 minutes) just off the coast. It has a couple of beach bars and a gorgeous beach. It's not generally very crowded. What are you looking for in a beach?

1st time to St.Maarten for me was on a cruise. We went to Orient, got bored then went to Dawn Beach. I loved Dawn Beach though I haven't been back since the Westin was built.
Pinel Island is great and Mullet Beach has beautiful clear water, nicest of them all I thought. They are all very different so it depends what you are looking for.

Thanks Sharona! Dawn Beach is kind of crowded now....by Mr. Busby's Beach Bar, there are new condos...and then on the other end is the Westin...if you want something less crowded, you want try Simpson Bay Beach...down by Mary's Boon or Karacters...or Mullet Beach by golf course...I totally agree about Pinel....$7.00 ferry...but watch your times if you're only there during a cruise stop...you'll have time..just allot for the ferry back and cab back to the port.....If you want something less crowded...maybe try happy bay..no facilities though....

One could Hang out at Orient all day. Great food & drinks. MUST go see Andy & Cheryl. You can get some shopping done as well. Then grab a cab to Sunset Beach Bar for Burgers & Beer. See the planes come in & hang out at that Beach.

Hi,
I didn't mind Dawn Beach at all.. I stayed nearby and was on my own and would take the drive and park at the Westin and used one of the lounge chairs at Dawn Beach. I had full access to all the ammenties - pool, bar (say hi to Oscar!) ATM, bathrooms..etc and had a great time swimming too! (A little rough though, but I'm a strong swimmer so it was fine).. I did venture to Mr. Busby's (a bar down the way from the Westin) via the water - I do not recommend doing this!!! It was a hairy experience trying to swim there - there are rocks to deal with and the water was very rough.. I was lucky to make it in one piece..although I did lose my sunglasses.. but I bought another pair in the Westin (quite reasonable price!)..thought I could "swim" over with sunglasses on but realized it wasn't the best idea half way there..it was nice to use all of what the Westin had to offer without actually staying there. The time share peddlers you will surely see but the beach is glorious. Hope this helps!