Check but I don't think there's a dive at the Renaissance, it sits on a cliff near the harbor so even their "beach" is around the pool on one side. Personally the Renaissance wouldn't be for me since it's right next to the Megaport cruiseport downtown.
Edited to remove links to the other Marriott (see below)
Scuba Lodge is also awkward for tanks if you're staying at the Renaissance. No boat dives from there and being on the fringes of the east side (Punda) of downtown (bisected by the harbor from the Renaissance) you'd have to drive back north over the bridge then south to get tanks. If you aren't planning to stay there it would not be convenient. Once we went to that area on a cruise day and traffic was so bad that after waiting about 1/2 hr. we parked in a field and walked in about a mile - it was really congested.
On the west side, there's Relaxed Guided Dives. Their location for tanks/fills is pretty convenient on the main road west just past the airport. If you dive West you're going to pass it every time. They also offer packages.
I'd guess over 10 days of diving, we used the on-site tanks about 1/2 the time. Some like Go West at Lodge KH just for the convenience, park in their lot right by the diveshop, down a flight of really bad stairs to their shop with lockers/restrooms/showers plus access to their dive dock that takes you far enough out to deeper water that you can stride off the end if the tide is in.
I don't have any recollection of what we paid for tanks onsite. Plus I was using up my guilders so I'm not even sure what I paid...lol But it wasn't enough to budget for. At some sites even if you show up with tanks, they may ask for a usage fee if you use any of their facilities/property. Some of the beach operators are pretty aggressive about it but for most tell them you're diving with the shop onsite and they'll leave you alone since it's included.
Sites where you'll definitely need tanks - Playa Jeremi, likely the Tugboat since the dive school there keeps closing/re-opening, Director's Bay, Pierbaai Beach.
Sites we rented on-site - Trunk Bay/Varsenbaai, Playa Kalki, Nos Kas (the old Habitat site) Porto Mari, 2-3 others I don't remember. Our first couple of days in Lagun, we rented from Discover Dive since they have a truck height loading dock and there were 7 of us so we actually rented a truck just to mostly haul tanks. Later we rented tanks from a since closed shop near town. Trunk Divers at Trunk Bay publishes the Curacao Shore Dive Guide.
I've read it both ways but unlike Bonaire our apt. mgr. told us to lock everything in the vehicles at the more remote sites. I've also heard Bonaire rules apply so I really don't know. Most times at a site with an operator they have a view of the parking area. One even volunteered to watch our vehicles if we pointed them out.