Hope it's OK to resurrect this thread...?

I'm planning a trip to Alaska for July/August 2015.
I can't get flight times yet but based on the current schedules my travel agent has said I could:

Qantas non-stop flight BNE-LAX arrive approx 06:40
Alaska Airways non-stop LAX-ANC depart approx 09:50
3 hrs layover

The travel agent said 3hrs on the way over is OK as the flights would be booked on one ticket.
The next non-stop flight to ANC doesn't depart until 19:00 so other than a day in LAX, the alternatives are stops via other cities.

Similarly coming home:
Alaska Airways non-stop ANC-LAX arrive approx 22:15
Qantas non-stop LAX-BNE depart approx 23:45
1.5hrs layover

On the way back, the travel agent says 1.5hrs would be OK as my flights would be on the one ticket, and I'd do my immigration and security checks in Anchorage and check my bags all the way through.
Alternatives again are stops via other cities, or a 1am departure out of ANC and a full in LAX before the non-stop flight.

(Not sure yet if I'll be flying Economy or Business Class.)

What do you think about those layovers - cutting it too fine?