The Emirates first class experience (including the DXB F Loinge) is unbeatable, IMO. It's my favorite F redemption, edging out Etihad and Singapore, which are also great. Unless you're flying those airlines, and I've been told CX, the points premium for F over Biz is usually not worth it. Having said that, if you were planning on earning 150K AS miles, why not make one more churn and get the 180 K needed for a rt F flight on Emirates? OTOH, you could consider this: Use 90K for a one way DXB to somewhere in NA on the Shower plane. Fly biz on something else for the outbound and then you decide if the extra ponts are worth it. Last time I did this in April, it was me, George Clooney and his fiancée as the only 3 people in F for 16 hours!
An all-world Biz experience is also one of AP's best redemption options: TK Biz, with no YQ! So I'd try to use your AP points for that, and your AS points for the former. My 2 cents. Plus, you can also get AS points from an SPG transfer. That's one thing that the Canadian CC world has better than the US: Amex MR transfers are better in Canada...2:1 v 3:1.