Awesome suggestions everyone, thanks

.
In order of price lowest to highest it appears to be:
Canon G10 (With some change to spare)
Panasonic LX3 (just about right)
Canon 400D (top end of my price range)
Canon 500D (out of my price range)
It's interesting the comments re the LX3 giving better picture quality; as someone with basic knowledge of photography my first impression looking at such a compact camera, is that the G10 would beat it. Is it a safe general statement that the bigger body cameras which (look like they) have larger lens will be better for night photography?
My primary use will be daytime and low light photos, but I really want to start taking photos at night (both portrait and scenery modes) which is why my old Canon IXUS compact is not up to the task. Running low ISO speeds and limited adjustments give lots of noise and poor colour saturation. Also I love that really lush, coloured photo that is often produced by professional photographers even in the daytime. Just look at the cruise photos that some of the regulars here take, and you can tell they aren't using compact cameras. If they ARE, then I want to know what cameras they are using

If I can stretch my budget the 400D looks good because it will allow expansion through new lens. My only concern is that photography is a deeeeeeeeeep rabbithole and I can't let myself get sucked in and spending thousands on lens later

. For those who have gone on to buy different lens, for what features do you usually buy new lens? I.e. super low light, high speed, super zoom etc.
Clarence: Something like the G10 is a manageable size; I don't expect to have to be able to carry the camera in my jeans pocket but at the same time it should be light and compact enough to chuck into a small shoulder bag for the day.