I've been playing with the 30 day free trial of Dobies (of Devon) garden planner software. I've not included the whole garden, and not used all the software's features, but I like it so far. I put in last year's plants and it warns me for this year's positions for healthy crop rotation which is handy. It can create a web page for mobile use which might be useful when I'm outside, although could result in a very muddy phone!
If you're interested, the webpage it generated is here.