Not likely to be on a package tour list,but C&N Hotel, Expat, Orchid Residence. Salathai maybe on it,these are guest friendly hotels where you can take back a lady without extra charge.
Most of the ones on that list dont like extra guests,and either refuse to let them enter the hotel (Holiday Inn) or have a very high charge.
You are leaving it very late to book somewhere now for Songkran,so you may be limited to what is available.
Good luck