I did my first solo drive with my kids last March from Southern Maryland to Raleigh, NC. It's about 6 hours - EASY! My kids were then 8, 6, and 4. The car was brand new (still had dealer tags) so there was no concern for safety...more about me getting lost since I have trouble getting out of an open bag :). But I did great! The kids were wonderful and we had the best weekend!
Since then, I have drivne 4 times to SC, an 8-9 hour drive, on my own with the kids. Twice my parents have followed me, we go to visit my sister. But twice I have done the drive 100% on my own.
My kids travel REALLY well. They sleep a lot, pack enough activites for themselves, and really just enjoy the ride. We go to the bathroom before we leave, don't stop until lunch time to eat and use the bathroom, and then drive again until we get there. They are good with that routine. If we drive with anyone else, we stop way more and the kids even get annoyed.
Your kids are old enough to do fine on the trip. Go for it!! Tell your husband he can support you or come along for the ride :).
ETA: I've been driving without my husband on long trips for a long time - just normally it's for a family thing so there are more cars and I'm not technically alone. But still...I'm grown :).