Delving into the middle tier

Hi folks,

Wondering if the bright minds of the forums may be able to shed some light on server technology combinations.

I am flash/flex developer. I am looking to branch out of the client side and maybe pick up a server technology. Specifically I am looking to build a RIA using Flex as the primary front end technology. There are sooooo many server technology combination I don’t even know where to begin. I do know that I want the following conditions to be met:
[]fa***st performance/response. I can’t count how many times I have worked on a flex project that was plagued with server performance issues. Generally this is attributed to how it talked to the service layer. Either it was stuck having to massage data or just waiting as a middle tier layer was talking with other middle tiers to aggregate data. I want to avoid both of these things
[]objects rather than XML translation. AMF? Remoting? I really have just cursory knowledge of these terms. How can they help me? I’d like to avoid WSDL too if at all possible.
]easy to work with. I am an OOP flex guy so I would like something that appeals to that mentality. I have tried looking at RoR. Maybe its just me, but its terribly simple sounding, but I can’t get my head around how or why it works. Call it OCD. I have it big time.[/LIST]I am sure this is a dream list. But any input regarding these issues is much appreciated. I really hope to avoid a religious debate on who likes what and why someone else’s choice sucks. But general pros and cons would be a big help.