The Flagship Problem: slim phones, slim batteries

I find myself missing my old 3310. Gone are the days when I could play snake for hours on end without having to worry about having to give my phone a "mid-day charge". I love modern smartphones and am currently rocking a HTC sensation, but these high end phones also carry around a sense of worry, will the battery make it through the day? This worry leads me to not using the phone to its full potential, turning features off and being afraid to use apps and games for too long just encase.

When Joe Blogs walks into a carrier/phone shop, a slim phone always looks great and battery life slips the mind. I can sympathies with phone producers; a slim phone will sell better than a similarly spec'd brick and they are only trying to compete in a market where slim is sexy. By the time the average user discovers their battery woes its far too late, they are locked in to a contract. The problem still persists: I want a decent battery life, I don't want to buy expensive battery extending cases, I am willing for my phone to pack on a few pounds.

What is the solution? I don't particularly want to carry around a 3310 and a smartphone, I still want a powerful smartphone and I'm not willing to pay a huge amount for a extended battery pack. Its nearly the end of my contract now, so at the moment it is looking like i may have to compromise and get the galaxy note and pull out my old 3310 back into service. I guess i can wait and see what the GS3 has to offer but the future is not looking well charged.

(Thanks for reading and I apologies in advance for any bad spelling or grammatical errors)