Not been to Sandtoft, but we went as a family to the East Anglia Transport centre last summer and all enjoyed it. The trolleybuses were doing a double loop round the site passing the rebuilt buildings - not that far, 6 or 7 mins each run maybe, but enough to get a feel for them (including some quite lively acceleration); the trams have an additional short run through some woodland. I think that the trams and trolleybuses were doing alternate runs when we were there, and the trolleybuses were able to run a couple of slightly different routes.
If I remember the opening hours were a bit unusual (not open in the morning?), so worth checking that, but certainly good for a couple of hours depending where your interest lies.
Hope that helps.
(PS we didn't do the light railway - it had derailed

).