Lately I've gotten serious about building bases. There are some problems I've noticed though. The hit box for some things for interacting with some things (fences, NPC's, anything small) seems to be very small. For NPCs in particular, you simply can't easily select or move them once they are placed somewhere with a lot of other items. Even if there aren't a lot of items, it's amazingly hard to select to move or interact with NPC's. This is really annoying. It also seems like moving things is very fiddly unless you're quite far away. This means if a floor gets moved accidentally in an outside room, and you have a roof built, it's extremely hard to reposition it accurately because you have to be too close because of the roof. This is made even worse with hard to select things like fences and iron gates, and completely impossible with NPCs.
I would also like to see some improvements on NPC's. It would be nice if there were options for children. We have wonderful playground items that can be chosen, and no one to put on them except full sized men and women in suits! If one is going to make a playground or school, it would be nice to be able to add students, or parents and children. Children sitting on those monkey bars. Children sitting on the swings! Lots of fun stuff could be built with child NPCs.
It might also be nice to change it so that there are only two kinds of NPC's, M and F, but assignable with the positions from the list of emotes. So if you place an NPC, you could select it and assign their position from a drop or list box, rather then picking from a huge list of NPCs with their positions assigned already. This may be impossible without changes that would be too hard - but I don't think it's bad putting the suggestion out there anyway.
It would also be nice to have a way to get NPCs with certain costume pieces like wings or specialty ears for those making themed bases (fey, elves, alien NPCs, hero NPCs), certain costumes (doctors for a medical area, technicians for a science lab, ravers for a club area). Maybe even swimsuits for a pool / jacuzzi area. It really helps a base come alive with proper NPC's. It would of course be great if we could get a custom NPC critter that was built like the AE, though I'm not holding my breath for that. It never hurts to suggest though!
Custom sounds assignable in rooms instead the entire base would also be great. Then clubs could have music without blaring it everywhere, and natural areas could sound - natural, without affecting your power rooms. There are all kinds of neat sound options now that seem to be unusable because everything affects the entire base. And if this has already been done but the guides are simply out of date, please let us know! I'm positive there are other base builders who'd like to assign the right kind of sounds to their rooms. That really is a must-have feature if you want to include any custom sounds. This is another thing that's really important for ambiance.
There is also a bug with glass panels of all types; they block FX! This means if you want to make something like a beam. or a jet trail - behind glass for safety, any of the marvelous affects you add are invisible from behind the glass! This is really annoying, as fences just aren't the same. If you build outside, you may want things with affects outside the room being built - and hiding those effects behind the glass defeats the purpose. This is particularly true if you want to set a base in space, or something flying through the air, and want to build things enclosed, but with stuff outside like a rocket or jet engine.