The lists above have some great climbs on them, but you would have to be a very efficient climber to climb all/some of the selected climbs on them given the amount of daylight available in late June when the daylengths are at their shortest.
Also my guess is that 20 is your comfortable limit, seeing as you are after routes in 14-20, so pushing your limit all day will also slow you down. The climbing at Araps takes a little getting used to as it can often be quite three dimensional and thought provoking.
I reckon 2 days at Araps will give you the most climbing by far.
For a fantastic day out do the first pitch of Kaiser (15), then into the next 3 pitches of Resignation (15). Then up Scorpion Direct (17) and into Blockbuster (12) which is a lovely gem or try your hand at Scorpion (18) or Quo Vadis (19) the latter two are solid for the grade. By that stage you are pretty much at one of the highest points on Mount Arapiles. Depending on the time left (you should allow about 20 mins to get down from the top of the cliff) you can try Missing Link (17 and a bit spaced, although you rap over the route so you could set up a top rope) or Thunder Crack (20). If you still have time at the end of the day then you can try Morfydd (19) or something on the Organ Pipes.
The next day you could head to the Northern Slabs and try some multipitches like Skink (18), Watchtower Crack (16) or Brolga (16). All absolutely fantastic. You will need a double (40m*2) rap to get down or an equally fast walk down the end of the cliff. So if the weather was good you could knock off two or all three of these. There are also some nice little routes at the top of the Northern Slabs (Claw (18) is lovely...)