When I was starting out, I found the Guest Spot series wonderful.
I have maybe 10 different ones for Alto.
But now I find them a little too easy and unchallenging.
They're good if I just fancy a blow without needing to think much.
My musical life is currently taken up with practicing for my grade 8 exam, and practicing for our Bands in the Park performance in 5 weeks time, that I haven't considered where to move on to for these books.
BTW, I see you're Worcester based.....you could pop over and watch us perform....Sunday 8th Sept, Malvern Priory Park, 2:30pm - 4:30pm. Single Reeds Saxophone Choir.