The Berghaus TwentyFourSeven range are really popular, no nonsense bags with sensible features and clean lines. Versatile, but not overly technical. The 20litre is a great size as its enough for waterproofs, food for the day and is hydration bladder compatible so you can drink on the go. The Flow back system has ventilated foam to keep you dry and comfortable and the chest strap gives a better, secure fit. There are internal zipped pockets and a key clip so you know where your valuables are and there's even a laptop sleeve for those commuting or on longer journeys.
This bag is lightweight and folds quite flat so why not take it on your hols as a useful daypack for souvenirs?