Hi, it looks much better to go on the 18th and return on the 25th.
On 17Apr, bos-clt has 23 and 12 open in Y for the flts you mentioned. on the 18th, there are 77 open on 1 of them - the other flt # didn't operate the 18th.
Clt-bze had 33 Y open on 17th, but 89 open on 18th.
BZE-clt has 53 open 24th, and 56 open 25th. clt-bos has only a couple seats open (no flt 1176 exists), but much more on the 25th.