IMO if there is to be a service off Crewe calling at MIA it should be one of the inter-reigonals, anything to make it 2tph between Wilmslow and MIA, preferably 2tph between CRE and MIA. Would make it significantly less difficult to get into MIA from the South.
And it would add by my reaconing about 10mins onto the journey time by having to reverse at MIA, it would be workable if it where a through station onto the Mid Cheshire Line and then it could be sent somthing like...
Piccadilly / Mayfeild - Manchester Airport - (Via Northwitch & Sandbatch) - Crewe - Non Stop Euston.
My reaconing is that about 40mins to Crewe could be acceived, but it would mean linespeed improvments galore.
When HS2 happens it should be and dear god I hope it is the case that the 'Manchester South Parkway' Station be a through station at Manchester Airport that can be served on route further north, and by services on route from London to Manchester.
Somthing like coming up from Rugley, the tracks would come into the Manchester Airport station, then have a delta junction for the Branch into Manchester, with about 10 platforms at 'Manchester International'
(In order from S to N, assuming the station is placed just N of the M56 Spur)
2 Northbound to WCML
Through Track
2 Northbound into Manchester
Through Track
2 Reversable for shuttles into Manchester
Through Track
2 Southbound from Manchester
Through Track
2 Southbound from WCML
I'd also provide a 'Manchester West Parkway' near the M62 & A580 just north of Birchwood, where HS2 would temporaraly join the Chat Moss line for Liverpool and the WCML, and run P&R Javalin services from both stations into Manchester via the Delta Junction at 4tph. BIIIIG Car Parks provided. (Off topic enough there?). Somthing like a Hitachi A Train in Northern Livery?