pbcup_sassault [Multiple paths, has jumps to increase speed on the map, but you can do everything walking] / or sandassault -> which is slightly slower pace.
pbcup_everglades [ Not many jumps, 2 ways into base. ]
Palmtreea [ Multiple paths, but only 1 'door' to flag ]
NML [ Multiple paths, 1 flag, every path you can walk straight to flag without trickjumps ]
OTH [ 2 flags, 2 high paths and a low, 2 flag can be gotten by a trick jump, or walking up a ramp from mid ]
Fusionr [ Simple map, 2 paths, 1 flag ]
ub_rooftop [ 1 flag, multiple paths ]
TFS / TFS2 [ Simple 1 flag maps with 2 or 3 paths ]
Some of the maps i've named could be small for 12-18, I'm not sure. But they are all rather simple maps with multiple routes. Hope it helps!