I was attending an academic conference held at the Hyatt by the Arch. We were very happy to discover Sen. It was many blocks from our hotel but it was a nice walk and well worth it. My trip coincided with the Missouri Valley Basketball "Arch Madness" tournament so the hotel restaurants and everything that resembled sports bars were totally over-run by basketball fans. During the week, a lot of the smaller places to eat close at the end of the work day, and on the weekend the sandwich shops and delis in this part of St Louis are pretty much closed completely. It seems that if you don't have a car or taxi, your options are limited. So finding Sen was particularly exciting.
The food was delicious. I eat Thai food a lot and the flavors here were spot on. They can adjust menu dishes to be more or less spicy upon request. Around our small group, we ordered the expected pad thai and fried rice standards, plus some nice curries and interesting noodle dishes. The meat was tender, the vegetables fresh. My sauce was a bit more salty than some I've had, but it wasn't a problem. The portions of food are generous and the mixed drinks are reasonably priced ($8 cocktails).
The decor and atmosphere are clean, warm, and right for a Thai place. It was easy enough to hear and have a good conversation with the others at our table. Service was a bit uneven - we had great service at the beginning of our dinner, but after the food arrived, we had to flag down a server when we wanted to order a second round of cocktails and have our water glasses refilled. But they did split the bill among the 6 seats without complaint.
I recommended the restaurant to others at the conference and would go back to Sen again.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.