March: Planning a dive trip for my boyfriend to get certified. Location recommendations?

Hi! I'm an AOW diver that has been diving for the last 15+ years. I prefer warm water and I do enjoy drift dives and deep dives. My boyfriend is going to take a referral course prior to the trip and get certified while we are on vacation.

What beautiful, tropical destinations would you recommend? Seems like the South Pacific is out. I'd prefer to avoid the rainy season, even if it's the tail end of it. We're based on the west coast of the US. We can plan for about 7-12 days of vacation. I'm hoping he can fall in love with a beautiful reef and lots of cool sea life.

TIA!!