If I needed to get a new car, and I had about $18,000, I'd get the Accord VP over the Civic EX.
The Accord VP (Value Package) is now the lowest level Accord. There is no DX anymore--no more Accords with window cranks. The Accord VP includes everything that most buyers wouldn't compromise on; the deal breakers: power windows, power locks with keyless remote, air, cruise, and safety, like ABS and
all the airbags. To keep the price low, it throws out little take-it-or-leave-it extras like variable intermitant wipers (the delay is fixed on the VP), alloy wheels, painted mirrors and door handles, auto off headlights, chrome window trim, extra-fuzzy dice, etc. (No sunroof, and I love sunroofs, but what are you going to do?) So it looks spartan, but it's got all of the most useful features, including safety features.
That just leaves the appearance. If you can live with the (relatively uncommon!) black mirrors and door handles, the lack of chrome window trim, and choose between the four colors, you can easily upgrade the wheels, or add a Honda spoiler or foglights. (And the stereo goes without saying, but shopping for a custom stereo is fun, right?)
On the other hand, for about the same price, you have the Civic EX. It's a brand new model, so it scores points in the me-first department, and it gets 40 MPG hwy (6 better than the stick or auto 4-cyl Accord), but the Accord is larger, quieter, and more powerful than the compact Civic. The Accord also has a new rear end that looks pretty good this time around, and it has cool LED tail lights, just like the cool but expensive BMWs

.
For $18,000, I'd rather start with the better car and upgrade a few things. The Civic is ready to go with no upgrades required, but the Accord is blank slate.
I'll take my '06 Accord VP in blue with a Honda spoiler, and shop tirerack.com for the rims, and crutchfield.com for the stereo.