AlbertaMS3, how tall are you and the husband and who drives when you are both out with the kids? I'm 6'1" and I really need the seat all the way back and see no room for a childseat, forward or rear facing, behind me when I drive. In fact, my son, who has out grown the booster, is hard pressed to sit behind me unless I move it up, which makes me uncomfortable.
Hi, it's Dwayne's wife, Jen again...
Dwayne is 6'3"... the seat can not be all the way back (passenger side), but it is back enough that it is comfortable enough for trips around town. He would not want to take a road trip sitting in the passenger seat. I have room to stretch my legs out in the same seat, but I am 5'7"... I do have long legs (wear a 34" inseam pant), but not as long as his.
Here's a shot of the resulting leg room in the front seat with the rear facing Marathon behind him. Please excuse the dinner plate and winter boots... he graciously came out for a quick shot during dinner.
http://farm1.static.flickr.com/165/429820374_2139bbb67c.jpg?v=0
Dwayne drives all the time with his seat all the way back when we are out as a family in the MS3. My 6 year old sits behind him in a Radian (forward facing harnessed seat) with enough room for his legs... actually, he has the exact same amount of room that an adult would have in that same position (which means not much

- but it is the same amount of room that anyone would have). The Radian is really nice because it is a low profile seat with no base and sits fairly far back in the vehicle seat. There's a picture of my 6 yo in it in my earlier post. It also has low sides, which means that it's easy for my 6 yo to cross his legs to get comfy for long trips (6+ hours).
Now that my 3 yo is forward facing, we have the Marathon forward facing behind DH and our 6 yo rides on the passenger side. At 3 yo, M has more than enough room for his legs behind Dwayne.
I know in another 3 years we'll just start taking other vehicles for trips... both boys are already taking after daddy and will be *tall*, so that backseat only works so well once you've got taller kids/adults in it.
Jen, CRST