The cyber range from superpet is good, as a Syrian can fit in the toys easily. Dig boxes are good, I have an old tub filled with sand and she adores it. They also like sitting on things rather than in things like dwarves, so the cube and bendy bridge mentioned would be good for that. I also gave mine a hammock which she enjoys. Basically anything big or anything raised with a flat enough top for them to sit on.
