Small has its advantages. I lived on Guam for two years in the early 1980s, and have enjoyed life on Saipan since 1990.
The climate in the Mariana Islands is considerably more humid than in Hawaii. the best months to visit are from mid-December through February or March. January through June is the "dry" season, though not in a California sense, but relatively speaking.
See generally Hilton Guam -- Still in one piece?
http://www.flyertalk.com/forum/showthread.php?t=131973
Hilton Guam
http://www.flyertalk.com/forum/showthread.php?t=128106
Hiltons in Guam & Saipan (there is no Hilton in SPN, but a Hyatt and Nikko)
http://www.flyertalk.com/forum/showthread.php?t=126712