We rent a car and self-drive from city (we then continued our journey to Borobudur). To my surprise GPS was reliable! I suggest you can try renting a car and drive if you want some adventure :) Overseas tourist, you can buy local simcard (from '3') with 2GB data (cost ard 20-30K rupiah) and use GPS from your smartphone.
Entrance ticket comes with a guided tour as well which makes it very informative. I have to admit that items that are being displayed are not many, but the good side is it won't be overwhelming. For me, it was enough to make me fall in love with the strong Javanese culture in Jogja and Solo. The architecture of the place was great.
Western food resto is available. They have good quality stuff in the shop. For ladies, you may consider shopping for batik dress here (price ard 600-800K rupiah). Much more worth it than those in Malioboro.