We stayed at the Papagayo Beach resort by Jan Thiel, and were very happy with it. There are other accomodation choices at Jan Thiel. We did shore diving at numerous spots around Curacao using Scuba Do, and our boat diving was done with Ocean Encounters. Interestingly, two of our boat dives provided by Ocean Encounters were right by Jan Thiel - I thought the diving there and at Directors Bay were great spots. We did not get to dive further west than Porto Marie on our trip last year, so next trip we'll try to hit more of the western sites.
Sites like Director's Bay, Tugboat, etc. are all very easily reached from the Jan Thiel area, as well as the diving right at Jan Thiel.
I'm sure Habitat Curacao has shore diving at their property.
The properties near the Curacao Seaquarium also advertise shore diving available.
If you go to Curacao, I recommend you take the day trip to Klein Curacao one day on the Mermaid.