I have sailed vessels from both CYOA and Island Yachts and am familiar with the staff at both operations. They are 1st class companies in every way. Both Frenchtown and Red Hook have good restaurants close by your charter base - both locations have provisioning choices within 5 min. by taxi - and both companies maintain their vessels to a high standard. CYOA will have a wider spectrum of vessel options, Island Yachts specializes in Island Packet monohulls.
For a 2 week vacation sailing starting in STT is an excellent idea - plenty of ST John anchorages to visit - most of which have a vastly different vibe than the popular BVI bar/restaurant mooring field crowd.
You can be at your charter base soon after you land at the STT airport - no ferries to deal with - dealing with BVI C&I is actually quite easy on a charter yacht, only the Captain has to appear and the paperwork is straightforward - for the return to the USVI everyone must appear at C&I but the paperwork is really simple [for US citzens].
I am not going to recommend the circumnavigation of STT - it can be a long slog around the West end and there are very limited comfortable overnight anchorages without having good local knowledge. You will find STJ, the E. end of STT, and the BVI in its entirety to be plenty of cruising ground anyway!!