I have found that often it might take 24 hours to get a full set of responses. I would imagine there are some people who come on here while at work because they have a computer there and not at home, or at home because they are too busy at work.... I often get a little down myself when I put out a request and don't get quick responses. I go to bed at night and am amazed when I have 7 replies in my email. Seems big spurts of response in early morning and evening after dinner.
On to your question though. I would suggest consulting the Honda Website. There might be some colors that aren't available in trims other than the EX. That would be one of your limitations. I have heard though that Honda has recently begun to offer Sunset Orange in LX and DX trims but I don't think their website mentions that. I think there are other colors that are exclusive to EX. So, also check a local dealer when you are ready and see what they can get you. One specific place to look if you want to know how one trim level compares to another is,
http://www.hondacars.com/models/specifications.asp?ModelName=Element
Then go through the Build and Price section, to see what colors etc. are available.
The primary difference, from what I have heard, with the DX and LX are AC and Radio Standard. I don't know where you live but you say AC is a must? If you drive a lot I would think a radio would be nice also. You can add those to a DX but especially with AC that is expensive. You might do well with the LX.
As for the EX, Side Airbag availability might be something to think of if you spend a lot of miles in the car. More miles more chance for an accident I guess. The plastic panels are, either painted or finished in some way to look a little nicer on the EX. Also don't have the problems with them with wax and other materials like you do with the LX and DX. Water Proof seats are available front and back in the EX and only Front in the LX and DX. Those are the biggest differences that I know of, between the EX and LX other than the better stereo and a few other comfort items. Not sure exactly what other features are different between all the trims without scouring the list mentioned above.
Doing a quick once over for you,
"Engineering" seems the same for all three vehicles.
All available with same Transmissions.
Body Suspension etc. seem the same but EX offers ABS and EBD(Electronic Brakeforce Distribution(?))
Steel wheels on LX and DX Alloy on EX.
Same Tires on all three(?)
Measurements are all the same
Each trim level is a little heavier than the previous. More Equipment???
EPA and Tank Capacities are the same.
Keyless Entry is standard on EX. Others an Option.
Power mirros on EX others manual (I like this when merging onto highways, can adjust mirror to see cars coming up behind and along side me)
Do you like Cruise Control? EX only.
Vanity Mirror, overhead storage and map lights EX. Vanity mirror I could live without but Overhead storage and map lights can be nice if you spend a lot of time in your car.
EX offers an additional 12v outlet in rear.
EX comes with front armrests others don't. (Can add those I guess).
EX stereo is higher grade with Subwoofer, 270watts 7 speakers Aux jack for MP3 or Digital Video, video games... etc.
Instrumentation seems same in all
Hope this is of help.
WmAS1960 (Bill)