1) I have my site as completely "public" - open to guests to view entire tree. I just now set it that way, because it was set to "mixed" - so far, when viewing the tree, it still shows some persons as "private such and such" - Are such changes dependent upon your "site refresh interval?" If so, you should let members know that fact.
2) BADLY needed "multiple-spouse" capability. I have yet to see any GEDCOM or other genealogy product recognize the fact that MANY PEOPLE have MULTIPLE SPOUSES throughout their lives - i.e. my mother was married SIX times - thus she would have spouse1 - spouse6 - and each would be connected to a different set of half-siblings, for example.
3) OPEN YOUR SEARCH COMPLETELY! When you *** REQUIRE *** people to register JUST TO 'SEARCH' for their family members, it HIGHLY DISCOURAGES them from joining! Look at MySpace as an example - they let you SEARCH FREELY to your heart's content - but when you want to POST/SAVE anything or contact members - THEN, AND ONLY THEN, are you required to register! You would see membership GREATLY INCREASE, if you allow FREE, OPEN, UNREGISTERED SEARCHES! This would be a ******* H-U-G-E ****** improvement and draw for your site!