I've enjoyed making a few maps for TD, but I wouldn't consider myself anything like an expert player.. Nonetheless -
There are maps in the official pool that are nice-looking or well made, but that I'm no particular fan of in terms of gameplay as they are a little chokey or tend toward more static games.. though in fairness, to remove any map with many choke points would reduce the variety in the pool, apart from the obvious point that this is all more or less subjective anyway.
The official maps should also tend more toward being well-detailed and attractive rather than sparse or abstract as these will tend to appeal more to new players, I think. A few more jungle maps would work well too as there was no jungle theatre in the original Westwood releases, and this will enforce a sense of 'newness' and novelty for the Openra version.
There is something of a paucity of 4v4 maps, and some additions in that category would be welcome, esp. given the popularity of big team games in the community.
Suggestions for addition:
1v1:
Tropic Thunder by Echo of Damnation: http://resource.openra.net/maps/17456/
Echo of Damnation has uploaded several maps to the resource centre lately and they are all really beautiful, aesthetically pleasing creations. Just from scanning over them in the editor, some may look a bit better than they play, but they're on a really excellent level in terms of the way that they're put together. This one is a low tib jungle map.
2v2:
-Crazy Canyon V2 by V: http://resource.openra.net/maps/17239/
Not played it, but this is a really cool looking map. River has multiple crossings, Tib fields should encourage expansion and it looks about open enough to allow some maneuver.
Riverside Frontline 02 by Marn: http://resource.openra.net/maps/12844/
Balanced, open, nice looking.
Sustain by roland kaiser: http://resource.openra.net/maps/16116/
Smallish, simple map with central tib trees that fill in new fields over the first minutes of the game.
3v3:
Inversion by pulse: http://resource.openra.net/maps/12882/
Tib layout can produce a strong 'frontline' across the centre which is mostly open.. Doesn't really encourage expansion except perhaps as a base push, but this is part of it's concept.
Back to Basics by pulse: http://resource.openra.net/maps/13423/
Very simple, clear map that encourages fast, fun games.
Ghost Valley by pulse: http://resource.openra.net/maps/13034/
Another that I've not played, but this has a cool 'theme' - a valley of destroyed buildings, with some visceroid creeps populating the central strip. Trees are placed in a visually appealing way, not too chokey, encourages expansion.
Aridification by Insert Name: http://resource.openra.net/maps/11820/
Open map. Nice 'desert' look and feel.
4v4:
Valley of Gold by myself: http://resource.openra.net/maps/15647/
Part of me wants not to suggest something which I have created.. But, here you go. Large, balanced, relatively sheltered starting areas, an open centre and narrow routes for flanking along the north and south.
Warchild by Echo of Damnation: http://resource.openra.net/maps/17178/
Playable as a 4v4 or a 2v2v2v2. Centre is a bit busy which restricts movement and I'd like to see it cleared out a little for that reason, but some good detailing and overall layout.
Suggestions for removal:
-Crossing the Rubicon
Sparsely detailed and tends to produce long, static games.
-Into the Valley Below
Good looking but very chokey.
-Simple Chord
Concept is fine, but strikes me as a little under-done and all of the trees in the middle are too samey.
Instant Karma
Nice looking, but there's only three crossings over the central river and no tiberium forward of the starting locations - not really to my taste.
Break of Day:
Torn about suggesting this as a removal as it is a beautiful looking map, but there are no zones for expansion, very limited options for flanking and there are many very narrow sections as well. There is an open-ish area in the north, but it doesn't really have an equivalent in the south.
Apologies for the wall o'text, ha - regards.