All foam mattresses, such as latex and memory foam, and innerspring mattresses with a thick coil gauge are a great choice for heavier people. Foam mattresses provide exceptional pressure relief and use foam cores to ensure proper spinal alignment and back support. They also tend to last longer than innerspring mattresses in the same price range.
If you want to keep your costs down, look for an innerspring mattress that has a tied coil system with thick coil gauges (below 15). In a tied coil system, the coils are linked together, resulting in a very solid, strong level of support. If you sleep with a partner and motion transfer is an issue, then you should consider an individually pocketed coil system with a thick coil gauge.