I had the same issue on my ipad2. I tried all the same things: clearing data, history, cookies, rebooting, restoring, closing all apps in the multitask bar, etc. Nothing helped. I had not had the issue until recently (after the last update). Checking the diagnogists I saw a lot of low memory crashes.
I finally found a thread on this forum from last year with some suggestions on optimizing memory on the ipad1. One suggestion was to turn off Spotlight search helpers. I don't use Spotlight so I turned all of them off. That was a couple of weeks ago and so for (knock on wood) no crashes since.
You might give it a try and see if it works for you. Settings>Spotlight Search
Thanks for sharing. I'll give it a try. Most of my crashes stopped when I cleared Safari history several times a day. Never used the history anyway. Apple will sort this out soon.