I will be in Aachen/Maastricht late April for a conference for a week. Will have all evenings (6-10 pm) available.
1. What are some good things to do in the Aachen/Maastricht area?
2. Is it worth renting a car for the week, or depend on local transportation? Rental works to ~300 euro. And I'll be staying at Kasteel Vaalsbroek
3. How do I find the distance from the Aachen station to Kasteel Vaalsbroek...its not available on the website.

link to Kasteel Vaalsbroek:
http://kasteelvaalsbroek.dolce.com/

interests are: castles, mountains, cruise, history, WW2.

These are two wonderful cities. Maastrichts is a lively old town, Aachen is full of history and and great buildings.
In Aachen, see the cathedral (Dom) where Charlemagne was crowned right in the year 800. Don't miss the treasury.
See also the gothic city hall. Don't miss to have supper at the Postwagen, a charming old restaurant that is right around the cathedral's corner. There are also several gourmet restaurants in Aachen. Here the links:
http://www.labecasse.de/
http://www.gourmetclassic.de/gastron...ne.Aachen.html
You may also read this article:
http://www.latimes.com/travel/destin...-travel-europe

Aachen is a lovely town to wander around in. The town hall is worth a visit, and you will enjoy all the bakeries; gingerbread in all sizes and shapes is a specialty. The open-air market is also pleasant. There are a number of good Thai restaurants.

I loved Maastricht. (Isn't there an international art festival going on in Maastricht in late April?)

You can take a train to Aachen, but it is a 90 minute ride one way, so that would eat up most of your evening.

There are several large WWII American cemeteries nearby if you are interested(you would need a car).

Are you sure that nothing has been arranged for those evenings? Is there no possibility you will be dining out with your fellow attendees? It seems odd to me that the conference planners would leave you at completely loose ends for the entire week. Doesn't the hotel have some kind of concierge service to help you with evening plans?

Between Aachen and Maastrict lies the American Military Cemetery at Margraten, just off to the south side of the main road and about at the halfway point between the two cities. It is the only American Military Cemetery on Dutch soil. Several others are nearby in Belgium. To find them, check the web site of the American Battle Monuments Commission.

It's a pity -- two beautiful historic cities only 22 miles apart, but there is no direct train service across the border. The train route is a ridiculous diversion as I learned years ago. Do you bicycle? It is a nice area. Maybe there is bus service?

Kasteel Vaalsbroek (in Vaals) is only 8.5 km from Aachen Hauptbahnhof.
It's a bit of a walk from the Aachen station to the centre.

wow! thats a lot of information for me to start the research.

BTilke: Dinner has been planned for all evenings, but I thought it might be an option to break away from the boring dinners for a couple of nights . I'd much rather travel around the area rather than sit in the hotel drinking/having dinner all evenings!

I do know the hotel has bicycles for rent..so that could be an option. I definitely plan to visit the cathedral (Charlemagne) and the WW2 cemeteries.

Well, you're going to have to source jetpacks from somewhere.

Aachen Cathedral closes for visits at 1900. It doesn't have even have Mass on Saturday evenings - and you're not going to be there in time for the Easter Vigil, which seems to be the only time in the year, apart from Xmas Eve, the place stays open late.

From memory, there are German local buses from Maastricht's Kerkrade suburb (where the border goes along the middle of the street, which is also lined with impressive tanktraps) into Aachen - but, also from memory, they don't originate in central Maastricht. Otherwise, a 20-30 min car drive. And, once things close in Aachen (which practically everything bar the Cathedral does by 1700), they close. Including - fortunately - the city's spectacularly pompous and self-satisfied town hall, with its bizarre gallery of the utter plonkers (Ted Heath!!!!) whose self-importance Europe's more useless politicians flatter by awarding the preposterous Prix Charlemagne every year for the shyster who's most cleverly run off with our taxes.

After which, apart from a couple of restaurants, the nearest worthwhile things I could find (and it is a few years since I used to spend weekday evenings in the area) were the bars of beautiful downtown Maastricht.

Which at least means you don't need to look aghast at pictures of just what out and out charlatans Aachen fetes every year.

and the art festival is between March 10-19!