My first scope was the Orion XT8 and only sold it because I've upgraded to the XT10. IMO, the extra few bucks to upgrade to the 8" is worth it, you get something like 70% more light gathering with an 8" mirror vs. a 6". A 6" will have no trouble with Jupiters moons, those can be seen with most binoculars actually. Uranus and Neptune will be visible, but faint. Titan will be visible as well. The 8" will really be a noticable upgrade when viewing deep sky objects. I'd even go so far as to say if due to your budget it's between a 6" Intelliscope vs. a non-intelliscope 8", I'd still pick the 8", though I prefer to find objects myself anyways. Either the 6" or the 8" XT dobs will make a fine scope.

As far as accessories, I'd get a very low power eyepeice as well as replace the 10mm that comes with the scope as it isn't very good IMO. IMO, plossl type eyepieces aren't any good below about 20mm as the eye relief is too short (you have to practically press your eyeball against the eyepiece) and the peephole you look through is tiny as well at shorter focal lengths. I'd recommend the 35mm Orion ultrascopic eyepiece for a very low power eyepeice (http://www.telescope.com/shopping/pr...ProductID=242). I had one with my 8" and it performed very well. You could also try a 2" eyepeice with a wider field of view since I believe the 8" is shipping with a 2" focuser, may as well take advantage of it. I have the 30mm Orion Stratus wide field eyepeice and use it a lot. (http://www.telescope.com/shopping/pr...roductID=73598) I'd also recommend the 9.5" ED-2 eyepiece (http://www.telescope.com/shopping/pr...iProductID=212) as an upgrade over the 10mm plossl that ships with the scope. It's got a nice long eye relief and a nice big hole to look through. You might also consider the Status line as a replacement for the 10mm plossl. You should also consider a decent barlow lens, the Orion Deepmap, and a Telrad. A Telrad is a 1X bullseye type finder. It projects a red bullseye when you look through it as opposed to a finderscope. I've been using a Telrad for years, and didn't even mount the finderscope when I got my 10".