Internet cell phone advice

I'm not much into cell phone tech and am happy with my 300i but it's starting to show it's age. My contract is up too so it's time to replace it. I'm on at&t in Colorado and would change networks but I need to keep the same number (business use). With that in mind I'd like a phone that can access the internet so I can check my gmail and web calendar and also access things that are handy on the road like news, weather and maps etc. I don't text much either. Any additional functionality would be handy like reading ebooks, camera, video etc. I don't particularly care about media like mp3 or video. I never use my current phone for playing mp3s and can't see that changing. I also see my internet usage being quite low so what plan would suit me?

I like the flip phone I have now as it's protected and very small but would like a decent sized screen for browsing. I use an online calendar with my wife so just being able to sync isn't as useful as real time checking of dates (we share a studio and need to check the availability before booking it).

As for cost, lowest possible. I'm not into flashy phones so the latest greatest isn't what I'm after. Tech from a while back would probably suit me fine.

What model/plan in your opinion is the best buy for me?