Sony Ericsson phones are fantastic
I had a Nokia 7610, I hated the fact that the volume was controlled by the thumb pad, very stupid idea and am I right in saying most current Nokia's are the same? So last year when my contract rang out I tried a V600I briefly but really hated the Vodafone branding, so I went back to Orange and got a K750I and haven't looked back, brilliant little phone. I am now due another upgrade and am waiting for the M600I and P990I to come out on Orange to see what there like, if there too big or exspensive then I'm getting a K800I as I have seen and played with it and it feels really solid in the hand and I know it'll be easy to use, I've hardly read the manual for the K750I.
You'll have trouble finding an easier Nokia to use as they all use Symbian OS60 version 3 the same as your N80 now apart from the bottom end models.
Go and look at a K800I, SE phones are VERY easy to use and feature packed with the best camera on a phone at the moment. You may also want to look at the K610I as it's nice and compact or the W850I for a sliding walkman phone.
Samsung are nice and the ultimate ones very thin, they are comming with 3G very soon as well.