ooh this is interesting, I've had to make the same decision. Thought I'd add my experience (although I haven't had the baby yet - due in December) in case anyone else is trying to make up their minds.
We were nearer Hinchingbrooke when we first moved to the area, and I had a miscarriage just before Christmas. We were treated really well through a pretty horrible time and when I found I was pregnant again, even though we were just about to move to somewhere a bit nearer the Rosie, I wanted to stick with Hinchingbrooke.
We're actually just about smack in the middle of the two hospitals so my midwife said it was totally up to me, so I chose Hinchingbrooke.
This hasn't been a very easy pregnancy and every time I am at Hinchingbrooke I think I have made the right decision, as they are lovely and have been very competent and helpful.
I am also being seen at Addenbrookes because of a complication involving my eyes; it's pregnancy related but I am being seen at the eye clinic there. Every time I go there I panic about the traffic and the sheer size of the hospital and feel glad that I'm planning to give birth at Hinchingbrooke. However I haven't been in the Rosie so this is based on nothing but my experience of the main hospital.
HOWEVER - what I have found quite stressful is dealing with a GP surgery and community midwives who are actually attached to the Rosie and know nothing about my hospital. My GP surgery is pretty fantastic, I think, but even my brilliant GP had to get me to go and call Hinchingbrooke myself this morning about my developing SPD as she didn't know how the physio department worked there, whereas she'd have known exactly what to do if I was being cared for at the Rosie. I've had to transfer my own notes between Addenbrookes and Hinchingbrooke regarding my eye complication and I have to get all test results printed out at Hinchingbrooke to give to my GP as they don't go automatically to my doctor, and in reverse, if I have any tests at my GP I have to be careful to chase them up as they go to the Rosie automatically. Also, the Rosie and Hinchingbrooke use different maternity notes - the Rosie use a yellow set, Hinchingbrooke use green notes. It's astonishing how much trouble that caused at the start, and still sometimes does.
As I say, each time I'm at Hinchingbrooke I feel I've made the right decision, but the logistics of the thing can make me feel quite stressed and upset at times and I still waver about it every couple of days...just something to bear in mind.