Qatar is not about oil, it's about natural gas.
Bahrain wasn't about Shiahs 1st, but more likely about the fact that a big Gulf US base could have eventually fallen in the hands of some eventual Iran allies, yes. Same island, same shiahs, but no base, maybe that would have been different.
Western Europe is diverse and is not condemned to be US allies, for my sake I live in a country that proved it (which might be one of the last advantages of this country).
Quatar is
primarily about natural gas, but they do have significant oil reserves.
Saudi-Arabia and UAE did not intervene to safe a US base from the Iranians, but to 1) prevent Iranian expansion across the Gulf and 2) safe the Bahraini monarchy. A popular uprising dethroning a Gulf State monarch would have set a dangerous example. You should not understate the second motive. Regarding the first motive the base was not crucial. Bahrain is at the doorstep of Saudi-Arabia and you can drive across.
http://en.wikipedia.org/wiki/King_Fahd_CausewayMost of Western Europe is still dependent on Middle Eastern oil, if we didn't have the Americans to secure these places we (and Japan and China) would have to do it ourselves. I find it unlikely China would be willing to do the dirty work, so Europe would have to get involved.