Reducing "you" from [ju] to [jə] is pretty marked as very colloquial, too colloquial a lot of the time. Something you might hear a show host say when faking enthusiasm, or a co-worker say when they're about to say something folksy ("an' I tell ya, those guys..."). Reducing "I" from [aɪ] to [ə] is a more normal thing to do, but it seems to me that it's mostly associated with speaking fast. So "I love you" would mostly just be [aɪˈlɐvju], and "he gives you a present" [hiˈgɪvzju əˈpɹ̥ɛzənt].
Reducing "him/her/them" to [ɪm ɚ əm] happens, especially in fast speech, but probably less often with "her" which I *think* usually retains the [h]. Maybe something to do with the agent suffix -er. There's nothing to remark about "me" [mi] and "us" [əs], as they can't be reduced any further. The possessive determiner "our" is almost always [ɑ˞], and the adjective (or whatever) "ours" is similarly [ɑ˞z] more often than not.
Well, in the North American Englishes I'm used to, anyway. Surely there's some dialect or other in Britain where "you" [jə] or who knows what else is normal...
When it comes to stress and prepositional phrases as in "I'm doing this for you", you asked a similar question in this thread back in July, when you received some discussion on this topic by Salmoneus and me (see Sal's post, my post and Sal's reply below, and some further discussion that ensued). Is there something about that discussion you'd like to concentrate on?
