Instead of looking up domain names on Domain Tools I would recommend something like https://instantdomainsearch.com/. It's using DNS queries so sometimes a taken domain name without any DNS records will show as available but that's a small trade-off considering the speed gain. It also enables you to do some invaluable brainstorming which is impossible using a submit-and-wait lookup.

Another tool I'm using frequently is http://www.leandomainsearch.com/ (originally a Show HN) where you put in a word and it will look up thousands of popular pre and suffix combinations in a second. The same DNS constraints applies but it's easy to click the domain name to see if it's really available.