I've done it before and it was enjoyable, but it does take you away from the circuit for a good half day. We dropped lucky and had a private tour of the Aston Martin coach works, which was amazing. Of course, the Retro Run does also give you the chance to do a lap of the track if you've not experienced that before.
You can purchase your event tickets from us and the Retro Run add-on from Silverstone for £99 + any fees, so getting back on our stand won't be a problem afterwards.
Hope that helps!