I agree with you @caringcarer dahlia are stunning and they keep flowering profusely all the way through to the first frosts.
I've added a photo to show that, despite struggling with the growing conditions this year, mine are just come into their own in Aug, with loads of new buds that will bring colour all through Sept.
When you uplift them, you trim off the long roots that hang off the tubers to tidy them up, then split them (plenty of tutorials online about how to do it correctly) and hose them off before storing them away, This way, you can easily double your tuber stock for next year, which is better value.
Ive also added a couple of photos of sweetpea which had been struggling due to the cold and rain, but in just 2 weeks have recovered well and now making up for lost time. Plus I planted a trough with lobelia, petunia, zinnia, and mixed herbs - thyme (which smells divine when you brush past it), sage, marjoram and oregano, for their foliage to fill in the gaps.