I live on Saipan, and Rota and Rubin dive are my among my favorite spots in Micronesia. You can still get there on Star Marianas from Saipan, as noted, but there is a 25 lb weight limit on baggage if you want to take your own gear. I ship my gear a couple of days ahead on Star Marianas, not terribly costly but a headache. Palau/Pelileu has a lot going for it, but it has become so crowded I am not planning on returning. On Saipan my favorite shop is Syd Takaheshi at Fishguyz dive group out of the Kanoa resort. He does mostly boat dives, which is my preference. He gets to Tinian frequently as well, weather permitting, if you are collecting islands dived. In the summer he can often get to the dive sites on the northern parts of the island, and there is Spotlight, a lovely cave with hole overhead and that magic shaft of light. Harry Blalock and Axe Murderers is a good dive operator, but I don't think he has his own boat if that is important (like the northern dives). I went with Speedy Tertel (sic) a couple of times, but did not care for it. Netterz007 is right about the cash... it is a headache, but it is pretty much standard on the smaller islands and often on Saipan and I've had to adjust.