Hi AeroSpark,
I'm a pilot for a well-known TOM competitor and our bread and butter during the summer is DLM. In the daytime, you can expect a sea breeze to have developed (wind from the south) so we land on R19 (the southerly facing runway) 99.99% of the time. At night, this breeze becomes a 'land breeze' and the wind will usually be from the north (or negligible) so R01 (the northerly runway) is the one most often used.
Obviously if it's dusk/dawn you are right on the transition in wind and the runway in use could be either.
The approach to R19 will have you approaching the airport (and valley) from the northwest - it's a VOR (non-precision) approach which is just designed to get the aircraft in to a position to break off and land visually early or, if the visibility is bad or the pilot wants to, it can lead you to flying to the overhead of the airport then turning back north (with the runway out the right hand windows) before turning final (heading out towards the sea again) after a few miles.
The R01 approach is an ILS which means it is a precision approach which will get the aircraft lined up on the runway very accurately. You can expect to, again, come in from the northwest (over the mountains - the terrain is one of the biggest considerations for pilots when operating in to DLM) and then be vectored left downwind (heading south, with the runway visible out the left windows) out over the sea before turning left, back north, to land.
So, in the day expect R19 and at night expect R01. If in the day you'll get some nice views of the mountains on the way in. Most pilots will fly in from the northwest, clear the terrain and, once visual with the airfield (usually around 15-20 miles away) will call 'visual' to ATC and fly a visual approach i.e. with reference to what's outside the window as opposed to the info from navigation beacons etc. It's quite a fun approach for us - once we see the runway we'll turn left (heading east) and follow a prominent road to get us in to a good position to turn 90 degrees right to land on the southerly runway.
Hope that helps!
B&S