There are three Hilton properties in the Maldives, with the SAii being a little, how to say, different. A few have suggested the clientele will be more of an Ibiza-type holidayer while Conrad Rangali and this property aren't so Ibiza-ish if you know what I mean - more conservative and 'quiet'. I really suggest spending some time on each resort's website, familiarizing yourself with the sizes and layouts, room types (including upgrade rates), emailing them for info such as weekly planners (which have a list of activities including excursions to do other things and visit other places), spa menus, restaurants and then compare the prices of each for all three properties. Only then will you really have a good understanding of what is going to be suitable for you and your budget. You can do Rangali on a reasonable budget and presumably the SAii as well but if you want to visit this property you will most likely, as you say, have to spend quite a bit more than the other two.