I have a son of 11, and has autism, just don't know what to get him for christmas, he does have a lot of toys, but still likes to line those up, the only way he plays with most of his toys is when we play with him, or working with him.. He loves his lego witch he plays normal with and also his cars, or drawing materials but he has loads... He loves playing outside, he has sandbox trampoline, and scotter which he plays with, he wont ride a bike..
I also have a daughter of nearly 2 which we got her a pram and kitchen, and just want to get him something special that he will enjoy,
how about an ipod. you can program it with his favorite songs. i always like board games. age appropriate board games are great and encourage socialization. i don't know how interested your son would be (due to his age) but if you say he still likes to line things up then perhaps you can encourage a train hobby for him. he can then line the trains and tracks up that are appropriate for that behavior.
My son, aged 6, loves 'baby toys' - especially little house type things, eg the teletubbies house, noddies house. He really loves his pink disneyland castle. People think that they belong to my older daughter...! He loves playing with 'push and ride' type toys, altho' he is too big!
We get ideas from adverts on childrens tv, we watch which ones he gets excited by ( he jumps and flaps). We also take him to our local massive toy store( just happens to be Toys are Us) and let him play and explore, we get ideas about what he would like from here mainly.
We have got over worrying about trying to be stereotypical 'toys for boys' and just go with the flow!
One word of warning - we sometimes have massive tantrums in the toy shop when it is time to leave without buying anything. We once got caught into the trap of buying him a little toy each time we went - BIG MISTAKE!
Good luck in finding the toy that is right, and don't worry if it doesnt seem to be age or gender appropriate - it's your son's happiness that is important.
(Thomas the Tank Engine has always been a favourite - the engines have great faces!)