It's not all temples on the road, there are a few interesting towns and Countries too !
Campeche is in Campeche ( State) Mexico. The Centro Historico is worthy of a stay over . Originally called San Fransisco, the walled City is beautifully laid out with a central park, colourful narrow streets and plenty of hotels/hostels and eateries. The seafront has a new pathway, a great view of the Gulf of Mexico, but alas no beach - otherwise it would be a popular resort.
Flores is a little paradise in Guatemala, that basically serves visitors to Tikal. But in it's own right, it is a great little place, an oasis of an island on Lake Peten. It has a path at the waters edge that will take you 15 minutes to walk around and a labyrinth of tiny back streets full of quaint cafes, restaurants and shops. There are water taxis and local interests to make this worth a few days stop-over.
St Elena is on the land side of the bridge and is a typically bustling Guatemalan market town, with tuc-tucs tearing up and down the narrow back streets.
Belize is a very small Country, with a very large tourist industry. Notoriously expensive, apart from the buses, it is a divers paradise of reefs and clear waters and a jungle trekkers heaven. In between is an impoverished nation, with few paved roads, almost non-existent garbage collection and general infrastructure. Hot and humid, insect ridden and expensive make this a visit for traveling die-hards only. Ps - don't forget the departure tax!
Beautiful and dramatic interior and lovely beaches when you can find a clean one ! Diverse races makes for an interesting mix of architecture and culture.