Avoid the tourist areas and head straight to Tolum. We took two buses (cabs will also take you there) to Tolum and avoided Cancun, Playa de Carmen. The ecoresort we stood at was right off the beach and had a great time. We rented some bikes, explored the town and the Tolum ruins. You definitely have to take a dip in the cenotes (watering holes). The cenotes are a great way to chill and spend a few hours in the sun and fresh water. Also, make sure you tell the cab driver what time to pick you up, otherwise plan on waiting for a cab. Chichinitza was also awsome and a must if you are in the Yucatan.
We did not know what to expect for Belize and were planning on chillin on the islands. Upon our arrival we stood in the city and headed to Caye Caulker in the afternoon. The island is not really developed for chillin on the beach and enjoying the sea. The island is really low key and not much to do, the highlight was our snorkeling tour to the blue hole(diving is available as well). We cut our trip short and headed to the jungle resort, which was great for hiking in the jungle and tubing in the caves.
We arrived in Flores and spent a couple of days. We arranged to visit Tikal, which was great as well. After Tikal we headed to Guatemala City and arrived at 7pm. We were planning on heading straight to Antigua, but the locals recommended we travel by day. So we ended up in the city and had a great steak dinner at an Argentinian Restaurant. We ended up in Antigua for about 5 days. We went to the market at Chichicastenango and had a great time getting some deals. Also, remember that you are a visitor and do not be rude to the locals. A European tourist was whining about the locals asking her for money. Guatemalans are poor, especially in Chichi so they are going to get their hustle on, deal with it you are priviledged. So if you need your personal space do not go to Chichi. Also, a highlight of our trip was the hike to the volcano. Take the last tour so you can see the sunset.