-Suvarnabhumi Airport:
If you have international flight from or to Suvarnabhumi Airport, you can take the Airport Rail Link skytrain to the last stop: Phaya Thai. From there the guesthouse is in a short walking distance.
-Don Muang Airport:
If you have domestic flight to Bangkok to Don Muang Airport, you can take public buses No. 59, 29 or 511 to Phaya Thai BTS.
-Hua Lumphong:
If you are traveling with train to Hua Lumphong train station, you can take the subway metro (MRT) from Hua Lumphong to Silom, where you can catch the BTS Skytrain to Siam, there you need to change lines (Sukhumvit line) to get to Phaya Thai.
Metered taxis are widely available everywhere in the city, also more adventureous spirits can take motocabs or tuk-tuks to Phaya Thai BTS station.