I've not done a pirate welcome but I made a pirate bag of goodies for our flight home.
There was Chocolate coins for treasure, pirate stickers, Pencils with skulls on,
You can add an eye patch, a bandana, fake ear-ring and a sword. A skull and cross bones tshirts or a Disney PoC one. The publisher Dk have a Pirate book in their eyewitness series that is educational, that we have at home.
Amazon has loads of fun pirate books. There is some great PoC
Lego out at the moment too which keeps little people busy when you are back in your room. Pirate balloons to decorate your room. A bedroom door hanger (surrender your booty at the door, or no landlubbers permitted) print and laminate (makes a good souvinerr for home). I've seen basic skulls and cross bones bracelet kits that kids could make up in the room and then they have something to wear at the parks and take home. Skull and crossbones flag for the room wall. Skull and crossbones pillow case. Pirate snap cards or top trumps. (I wish I'd added more to my pirate bag now!)
I Made a pirate passport (more of an activity book). I decorated it with clip art and lovely DISigns from here.
Add a photo of your 'pirate', other passport information: age' name of ship, job on ship, favourite treasure.
Then i added colouring pages, crosswords and wordsearches etc with a pirate theme. I made a pocket for a treasure map and printed out a blank map for DS to decorate himself. I also made pirate pendants from DISigns printede onto paper, laminated and then corded (won't last ages, but they are fun)
Websites for pirate printables to make your own pirate activity book:
http://printables4kids.com/
http://www.dltk-kids.com/crafts/pirates/printables.htm
http://printables.kaboose.com/pirate-printables.html
http://family.go.com/disney/pkg-disney-pirate-crafts-and-recipes/ (I wanted to make the voodoo doll from this site, but ran out of time- maybe next time!)
http://www.homeschoolshare.com/pirates.php (I Made a few activity books for our trip, ad I really liked the America homeschool stuff that uses lap books, as the activities were engaging to keep DS busy, but they were educational at the same time)
I printed the passport on a5 paper and then added a plastic sheet front and back and spiral binded it all.