I'm a masters student at Oxford right now and I haven't really run into any class issues. I think class divisions are more obvious/prevalent at the undergraduate level. As a graduate, you're surrounded by tons of international students from a huge range of backgrounds, many of whom are on scholarships either from Oxford or their home countries, so their personal wealth is not such an issue. At our orientation they told us that 65% of their graduates are international, so it's a pretty mixed bunch. I've encountered some arrogant people here, but no more than I did in my undergrad in North America.
Tuition is certainly high if you don't have any scholarships, though it's not high compared to unfunded degrees in the US. The only glaring money/class issue I can think of is how many expensive events there are here that you can go to, such as college balls and that sort of thing. But you can definitely do a ton of stuff and have an amazing experience even without such events since there are a million free (or very very cheap) lectures/seminars/parties/etc.
So, that's just my personal experience. My impression is the undergraduate and graduate experience is extremely different here. And a lot of it is what you make of it. Sure, you'll find arrogant people. But you can just ignore them and find your own crowd instead. I imagine the same is true at Ivies.