It's so popular that I assume you've already thought to include it, but Sphax PureBDCraft is a great texture pack. Here's the link to the 256x version but they have versions all the way down to 16x. http://www.planetminecraft.com/texture_pack/sphax-purebdcraft-x256-v0658-for-mc17/ I recommend playing on at least 64x to get the full effect. The armor looks especially great in my opinion.
Well the issue here is that Mojang changed the file type that map files are saved as. Orignally, they were saved in a format called "Region", and now they use a format called "Anvil". In addition to doubling the heightmap limit, they changed a lot of the algorithms used to generate worlds. Unless you can find a mod that inserts the new blocks and items into your 1.1 world, I don't believe there is any workaround.