Yeah, sounds like some adjusting to your strap angles and placement is key. Most good snowboard shops can help with this.

I've had good experiences with boot fitting at both the Burton flagship store (the original, not the downtown one) and at Alpine Shop.

I now use a semi-custom footbed in my snowboard boots, ski boots, hiking boots, and daily shoes (I have pretty high arches). Makes a big difference.

If you can't get the straps to ever work nicely, I switched to Burton Step-On boots/bindings last year for the days I'm riding...huge improvement for a 40+ y/o with a lot of aches and injuries...no more struggling to strap in, or struggling to get out (also a big help when working with young 'uns). Not cheap, since you need to buy new boots and bindings together, but I found it worth it.