We will return To Alaska next summer ( 2019) and will use either our companion fare voucher or our AS miles, of which we have quite a few. My question concerns the miles booking.

i plan to book when the award seats are released, around T-330. Looking at those flights now ( thus late March 2019 flights) Insee a mix of award levels, starting with 10K then 20K then 30 K for Economy. Do they release a limited number of seats at the 10k level and then raise it to 20K and then 30 K as those are taken? It seems a bit odd that the seats going to ANC in late March would be so popular and be booked so far in advance. Or maybe this reflects Iditarod schedule?

are the seats at all three miles levels the same ( Economy) or are the 30K seats actually the Premium Economy seats up forward innthe cabin? And do they ever release Economy Basic as award seats?