Thanks for all the input everyone!
I ended up getting a Kindle Paperwhite.
I found that as some had said, if I emailed the MOBI to the Kindle Email Address for that device, then performed a sync on my android phone with the Kindle App, the books do in fact sync last read page just fine, which was the whole point of what my original question was about.
I do wish there was a way to bulk import books to the device and sync them to her phone as well (as another had posted, copying them to the paperwhite via USB does not accomplish this), but this accomplished what I needed overall.
Now we will just have to wait a few weeks until I give it to her and see if she likes/uses it.
Almost makes me want to start reading again playing with it!
Thanks again for the ideas/help/suggestions/etc everyone.
Oh, and as a side note, seeing as it was mentioned by a few folks- she has a Nexus 7 already, so I suppose I could have just done the Kindle App on there as well, but with summer being here, I figured she would want to read more outside on the patio, and the Paperwhite sounds like it excels at that.