Footsmart.com has lots of shoes and orthotics and they'll recommend ones for plantar fasciitis. I haven't seen anyone else say this--get a ball of a comfortable size to roll the bottom of your feet on. For me, it's a golf ball. Stick it in the fridge if you want some cold relief. It really does help and it breaks up scar tissue. (Or am I the only one who has scar tissue in their arches?)
I went to an actual "prescription" shoe store, sent by my podiatrist. I would definitely recommend someplace where you can get personal service--even a running shoe store, someplace where they will still actually fit you. You didn't say what caused your plantar fasciitis or what shape your foot is. What makes you feel better will really depend on things like having a high or low arch or whether you pronate or supinate. Lots of people also don't realize that shoes come in sizes wider than normal and wide. (I wear a 6EE) I was told to make sure to get a shoe with LOTS of support, that you can't bend in half. I wear Dr. Brooks. (BTW, if your feet get cold easily, don't get the breathable fabric, go for the leather uppers.) Don't be afraid to try on different shoes to get the right ones. They're going to cost enough moola that you should get your money's worth.
BTW, I have heard really good things about the shoes with the springs in the heels, and they're highly recommended by the shoe store where I do business. But they're even more expensive than the shoes I buy! I guess you have to balance price against how comfortable they're going to make you.
I'm a long-time sufferer with plantar fasciitis. I don't know if I waited too long to get treated--I have a history of thinking I'm a big wuss if I seek treatment--or if I'm not able to be cured because the cause (very high arches) never go away. I have lovely arch supports from my lovely shoe store, and I do my stretches every day or I pay for it, and standing for extended periods of time is out of the question, but for the most part I'm fine if I watch myself. Please, please seriously consider renting an
ECV. It makes a *world* of difference, and it doesn't matter what anyone else thinks. If you're in tears from the pain at the end of the day, you won't be having a good vacation.
ETA--ooh I forgot. You don't have to give up your excercise, but you can switch to low-impact machines. The stationary or recumbent bike is good, and 24hr fitness swears that the eliptical machine is low-impact. (I have my doubts) Water aerobics would be good, too. I'm amazed that your doctor okayed the treadmill, though. Make sure you stretch before you do any excercise, and I mean your special plantar fasciitis stretches!