take it to the paper? 
we're only getting one side of the story here. in my own experience, both at the local starbucks near my parents and the one near us, staff are actually too lax imho. i used it when i was at home all the time, it was a good place where i could predict how busy it was and how child-friendly it was (good changing facilities, i mean)
but some mothers really take the micky, blocking up the walkways with buggies, buying 1 coffee and spending hours there - and when they leave, it looks like a bomb site. i know this is the case at my local one these days - there is a group of women who meet up there every tuesday (maybe other days too - i only used to go tuesdays as it was my day off), they leave the place a tip and i feel really sorry for the poor staff there.
so, if you're one of THOSE mums, YABU. you've been booted out for a reason.
but if you're not one of those mums, then you might not be being unreasonable.
only your behaviour in context would really let us decide properly - can you explain more info on how you use the place, do all 8 of you take buggies, how big is the space, do you leave a mess?
i will admit that i've never seen a starbucks banning a woman because she has children with her but i have seen overworked staff who'd be perfectly justified to do so, imho, based on what i've seen. on the other hand i can see that if the hotel just doesn't want to encourage kid custom, then that's annoying and unfortunate, but they're entitled to target the customers they want to market too - move on.
so, which is it - are you a pain in the neck for these places, or just the wrong target market?