Toys worth having for a LONG time

A lot of thought went into what were were going to bring in our suitcases to Maryland to live with for these first two months while our apartment is in storage.  A good amount of room was set aside for toys.  Toys are my sanity!  They are also a big investment.  So far we have been surviving well on what I was able to pack into our suitcases but tonight I got to thinking about what toys we own that stand out to me and why.  Most of them had one or more of the following qualities: 

Durability- something that doesn't break or come apart easily is a must for mommy's sanity and pocket book;
Creativity- has more than one use and allows the boys to use their imagination in different ways;
Longevity- I want a toy that we will go to again and again that also interest multiple age groups (me included).

Here is my list (what comes to mind right now) and suggestions on where to find them.  I would love to know what toys you have that fit one or more of the above qualities.  Please share!

• Kid K'nex - don't confuse them with K'nex which is geared toward the older crowd with LOTS of tiny pieces (and are also pretty cool, we have the dinosaur set).   Kid K'nex is the younger brother.  They are bulkier, sturdier, and very versitile.   They stick together easily and aren't frustrating for Sam (3 yrs) to put together and take apart by himself.  There are a plethura of different kinds of sets, each with their own set of instructions.  They come with quirky creative pieces in addition to the standard pieces.  Elijah is notorious for making guns, swords and aliens; can you tell he is five?  Kid K'nex are great toys to get second hand because the are so durable.  I got most of my Kid K'nex at a consigment store or garage sales.  You can also find them at your local stores though the selection is very limited.  You can see more at Kid K'nex's website. (I am not familiar with the new blocks sets)
• Fisherprice GeoTrax- If your boy loves trains these are totally the way to go (sorry Thomas wood trains, you don't even compare).  Again very durable with so many options.  You can make a different track every time you get it out.  The options are endless.  The electric trains are also really nice though they do take 6 (yes SIX) AAA batteries each.  Older kids 4+ can build their own tracks without help from mom (yay!) though I've found that building the track is actually a fun mental challenge.  GeoTrax can be a bit pricy but because they are so durable they are another toy that is excellent second hand.  Consignment stores are likely your best bet.  Also watch http://www.craigslist.com/ or http://www.ebay.com/ for local sales.
• Legos and Lego Duplo- depending on the age of your child these are a staple building block to have.  We are just getting into the standard sized legos and Elijah is eating them up (not literally, he is 5).  Legos call back to my own childhood and my sisters (10 and 12) are even still playing with the legos I grew up with.  Legos don't die! Plus the creative possibilites are endless!  Duplos are the bigger blocks for smaller hands but their size doesn't limit the creative possibilites.  New Lego sets are nice in that the come with instructions for the kids to study and follow.  You can also find patterns online.  Buying secondhand is the economical way to do it though you will find that legos maintain their value.  Garage sales are a good bet.  Always keep your eyes out for them, you will not regret it.
• Wii- I know, I know... it's a video game system not a toy but right now it has saved me many a painful afternoon and it is something we enjoy playing.  Our family focuses on games that are multi-player and are active.  Many of the games teach sharing, turn taking, rules and mechanics of sports, thinking, team playing, etc... So maybe one paticular game doesn't fall under my list of qualities but the system itself is ingenious and not completely pointless fun.