If you are having hand issues, you might have your fit to the bike set up wrong. Possibly your STI's aren't in the right position on the drops or you just are holding them wrong. IMO, the weight on your hands should not be on the rear part of your palms.

You might find that lots of padding isn't any better for long rides. Or maybe even worse. I prefer cycling gloves with just a leather or faux leather palm. Though they've become hard to find since the mfr's and ad people made gel sound like the end all do all for any discomfort. Which it's not.