It is mostly used as a place suffix, as you mentioned,
some times indicates the affluence of that noun (in that place of course). for example:
golestan / گلستان / means rosary or a place that has plentiful flowers "gol".
some times indicates just the place of something. like:
farhangestan / فرهنگستان / means academy or a place of study or training.
if you use it with a "Proper Noun" it indicates the seat of that noun. As:
Turkestan / ترکستان / means the place that Turkish guys settled.
and some times used as a time suffix:
tabestan / تابستان / which means summer
but generally you can consider it as a place suffix.
hope to be useful.