Day of week? Exact date better. How many travelers?

Arriving flight at DMK is domestic? International? Checked bags?

The inter-airport bus may be the best option given the taxi queue problems at DMK.

Shuttle bus to Don Mueang - Suvarnabhumi

Park waiting to serve only passengers. Don Mueang Airport And Suvarnabhumi Airport On the 1st floor entrance platform, gate 5, Terminal 1
, free of charge. The user must show the boarding pass to the driver before using this service.

http://donmueangairportthai.com/en/3...blic-transport


I'd say you should be fine with the bus or a taxi, unless there are some unusual circumstances. We've had a series of tropical storms over the past few weeks, with some of the heaviest rains I've ever seen here. All roads are flooded and delays of up to several hours are not unusual.