I am about 100% on getting suites at HI/HIX and usually get 2 category (this can be meaningless with all the classes) at ICs. Always goes from classic to premium if I book a standard room. Return visits probably have more impact than any loyalty benefits.

I keep the expectations low and when I really want a suite I book that or use a SNU

I think all hotel groups are pretty much the same to be honest on this.