Do you want a sealant, or a wax?
I noticed in your 'Readers Rides' post that you used the Meguiars 3-step system; whatever you decide to use to protect the car, it will be more efficient than Meguiars' step-3! IIRC, their Step-2, the polish, is a 'pure polish'. More of a glaze (no polishing (abrasive) abilities)
I'm not sure if you caught it the first time round Paul, but, take a look at this
Audi S3 in black that I worked on. This was protected with Dodo Juice Supernatural. 90% of the overall look however is down to the prep work before the LSP (Last Stage Product)
If you want to stick with Dodo, try their Purple Haze wax (As JonJay pointed out earlier), or, their "Blue Velvet". Both of which are colour charged for darker coloured cars.
*Edit - and, if you want to get rid of swirls.. by hand it's always going to be a challenge. If you were knackered after your 2 hour session cleaning it last time, you may struggle with working the lot by hand

Dodo Juice Limeprime would probably be my first choice. As said above, with it's micro-abrasives it has 'bite' to it and can certainly reduce the lighter surface swirls and scratches, even by hand.
AutoGlym Super Resin Polish could be worth a try if you haven't already? Although correctional abilities are low with this, it's full of fillers that, in turn, 'remove' (hide!!) the swirls for a period of time.
Then you could try Meguiars Ultimate Compound (I think..) I don't know too much about this one, but, saw a demo of it at Megs HQ in Daventry late last year and the results were pleasing.