Will the OP only need to buy a (slightly cheaper) bus & tram only daysaver, as his journey from Denton to Stalybridge then on to Manchester will be covered by his Stoke-Denton return?
Stoke to Denton would be valid via Guide Bridge, but if the OP is continuing to Stalybridge by rail then it's dubious whether it's valid via Stalybridge, however I say that without checking the Routeing Guide. If you've checked and that's valid then fine but I'd try to obtain an itinerary in case of any disputes.
Having said all that, due to the minimum fare, a return from Stoke to Stalybridge is going to cost the same price (£12) anyway.
I personally would get the Denton ticket for the novelty factor (and to boost the stats
) and get the inclusive rail & tram ticket, as some of those Metrolink branches are best done in combination with rail journeys. On the other hand, the ability to use buses would also be useful.
Without going too off-topic, Greater Manchester PTE (or whatever they call themselves these days) has a rather daft pricing strategy, with a complicated array of fares, which penalises passengers for using multiple modes.
The Wayfarer is fantastic value, and gets round the evening peak restrictions, but is a waste if it's mostly being used for Metrolink.