In my experience, no.
I am a multi-year Plat who also went to the St. Kitts Marriott (in October) on a similar deal but for a 4 night stay. I also booked the lowest room category available.
When we arrived, we were told we were upgraded. Our room was in the main building, which is quite a stretch from the ocean. We overlooked a lot of gardens, a sliver of pool, and I think waaaaaaaay off in the distance was the ocean.
Since you will be there for a full week in June, I would think your chances of getting an oceanfront room would be slimmer than my chances for 4 nights in what was a slow time for them.
You can surely push them for the upgrade at check-in, but for a 7 night stay your odds would be less. Maybe you'll be luckier than we were.
Having said that, we really liked the resort and loved the island. I think it is a hidden gem of the Caribbean. The people couldn't be friendlier. The Marriott is basically the only name hotel on the island and the locals are very appreciative of all that the Marriott and it's (perceived) wealthy guests bring to the island. Crime is minimal on this island and at no time did I ever feel unsafe (well, be careful down by the docks, but that was about it).
Drinks at the pool are cheap during happy hour. Don't miss that if it's important to you (4-6p, as I recall).
Pick a cabdriver and stick with him the entire trip. Sounds funny but it is a small island and the cab drivers can be your lifeline to good restaurants and things to do.
I really liked it here. I know development will spoil this island within the next 10 years so you are fortunate to be going before everyone else gets in on it. Oh, and we went to Nevis. The boat ride was great but the island itself was a waste, to us at least. Unless the Four Seasons has reopened, there is nothing there. (Just checked...not reopening until November.)
It's pretty and the island is very laid back. The casino did us no favors

Hope you have a fantastic time!