Cell phones: I Want A Phone Not Offered By Sprint

I Want A Phone Not Offered By Sprint

Hi. I'm looking for a new cell phone but not necessarily a new carrier. My carrier is Sprint, my phone is a Samsung A920. I'm pretty happy with it, except I'd like a bigger screen (easier on the eyes). I like all the multi-media and internet capabilities on my phone so the phone I'm looking for needs to have the same or better capabilities.

I am not really impressed by anything I've seen offered at my local Sprint store or at sprint online. I would like to know- how limited am I, as far as phone selection- if I stay with Sprint but want a phone that Sprint doesn't offer? For example, could I get a LG enV, one of the Nokia Es, or Rim Blackberry Pearl? If it is possible to get a phone not offered by Sprint, what are the guidelines or limitations I should stick to? Also, if it's possible to purchase a phone from another company, what does Sprint "do" to activate it? Hope I'm explaining myself!

Thanks,

Carrie