popay is right: Gear down, flaps 3, speed brakes out certainly gives you the best descent gradient.
What I use is this: at Green dot, simultaneously select Flap 1, full SB, gear down, Open descent (with say MSA selected in the alt window), Flap 2 and 3. Select 179 KIAS and you should end up with about a 9 degree descent at 3600 fpm ROD. Approaching 4-5000' (depending on your MSA), wind up the selected altitude (don't pull!) to above your current height and select (don't pull) 2500 fpm VS.
With this profile you can be at 20,000' with 27 to 30 nm track miles to touchdown.
Regarding popay's 3000 fpm ROD, my other life (low level single seat over water) taught me to look out for "one minute to death": ie at 9000' alt you should have less than 9000 fpm ROD, at 5000' less than 5000 fpm ROD etc. These numbers are obviously excessive for an airline operation, but surprisingly easy to exceed below 2000' if you are trying to capture the GS from above.