Hi Aaron,
Regarding eyepieces, I strongly recommend waiting a couple of months before doing anything. Asking what eyepiece to get is a huge question- unless you do a crash course in it's education, my advice is to hold off and get a feel for the equipment & eyepieces that come with the scope first, then you will have a better idea of what it is you want. There are so many factors not forgetting your budget that comes into it. When you are ready, have an extensive read through the eyepieces forum- go back as far as you can and read through the threads. Then you will be in a better position to ask that question I think.
Go the 10" dob if you can afford it. It's the same length tube as the 8", but the base is a bit bigger I think. Still not a problem though fitting in both into a med/large car. You should make sure it's going to fit before you buy just to be safe. I lay the tube on the backseat strapping the seat belts around it and the base goes in the back (or whatever fits best). Wheels attached to the base or a $20 trolley from Bunnings is helpful to move it around the yard as it's quite a bit heavier than the 8", but the views it will give will last you a long time before you feel the need to upgrade (if you do). I see loads of galaxies thru it from my light polluted backyard.
Also, if you get the 8" and decide to upgrade, you'd probably need to jump to a 12" to see a big difference. The upside is the 12" is also sold as collapsible & transport shouldn't be an issue, moving it around might be tho. Me, I went from a 6" to the 10" as thankfully the guys talked me out of making the small jump from the 6" to the 8" as I originally was going to. There was a huge difference in the Orion Nebula making that jump.
Having said all of that, an 8" is a popular size and known to show plenty of objects.
Perhaps you can meet up with a local astro club- I'm sure they will be more than happy to let you look thru their scopes.
Have a look at my target list for July/Aug
here. Most should be observable in an 8" dob (except for the difficult section). Some may require a dark site, but many will be achievable observing through light pollution. Some good tips in there too if you keep reading thru the thread.
P.S. Saturn is a jaw dropper in a 6", so in an 8" it'll be amazing also.