I much prefer the Eau Claire Suites hotel. From my experience, larger rooms, terrific Club level lounge with nice evening and morning fare, terrific management, trendier, small waterslide etc. The Westin, although decent, seems rather plain by comparison. Guaranteed Club level rooms can be had for quite reasonable rates and are very nice w/ amenities etc provided. Valet parking is @$20 CAD in both hotels. Suites at the Eau Claire are likely to be larger than anything you will be upgraded to at the Westin and the Eau Claire is a guaranteed suite.
If you need anything else, PM me.
and welcome to Calgary !