@Stuart ********
14 day trips shouldn't be a major issue actually. I know countless people that have been using Bangkok as a hub for such trips, though usually they don't enter Thailand 14 times a month, sometimes they do come and go up to 5 times a month with each entry rarely, if ever, exceeding 7 days. Usually it's just 1-3 days. They've never once faced any problems doing this.
Now they also don't do this every month. It might be once every 3 months that such a trip comes along. They fly to Bangkok, spend 2 nights then it's off to China for 10 days. Back to Thailand for 2 days, then it's India for a week. Finally, back to Thailand for one night and off home again. Rinse and repeat 2 or 3 months later, with a slightly different itinerary. This time, using Bangkok as a hub for travel to Vietnam and Malaysia, for example.