Like meanee, I just leave my computer on with sleep disabled. Simplest solution.
Also, Splashtop is not that hard to set up for 3G if you've ever had to set up your home network for IRC, BitTorrent, etc. It's just basic port forwarding. If you haven't ever then I guess it can seem difficult. When I got the app, I just googled instructions and had it set up in under five minutes.
Also, worth every cent of the measly $2 I spent (it was on sale). I spent forever agonizing over whether to spend $30 on LogMeIn and I'm glad I waited cause while LogMeIn has some nice extra features, from what I have researched, they aren't worth $28 more, especially considering Splashtop works quite excellently as is. I use it all the time at work to control my home downloads and also to grab files that I forgot (I use Dropbox) and to do various tasks that I can't on my work computer (i.e. Create PDF out of TIF files, simple Photoshop stuff, maybe handle some video compression, etc). It's also pretty amazing how well the video and audio work - I can basically access my entire music collection using it. Hd video isn't flawless motionwise but it's closer than you might expect, the video quality looks very good and it is watchable over wifi. 3G is a LOT slower than wifi use but that's more the fault of the connection than the app.
