Wife originally bought us a HD expandable, when it was over two years well used a zipper failed so I went on the look, found BESTEM LGHD-GLIDE bag, fit and shape is similar to the HD, expands from the bottom similarly while is heavier nylon with heavier zippers. When I had a zipper seam fail I called to get the name for a repair service as I loved the bag, they sent with no questions a new bag FREE and free ship, had it in three days, awesome customer service.

 

I've used
1) canvas duffle bag with bungee cords
2) SAC tour pak rack bag - fully and completely waterproof
3) t-bags boot case.
My wife gets the rack bag and I get the tourpak. my stuff is bigger. Saddlebags are for riding gear/tools. we can pack for 1 week without having to do laundry. we travelled 14 days last year and did laundry once. this year we are going for 3 weeks so will do laundry twice.
am looking at the t-bags Dekker II. found it on amazon for almost $60 off with free shipping.

 

I use the HD collapsible bag for $99. I usually try not to use it but it seems we come back from trips with more then we started. Bag sits in bottom of tourpak when not in use but it will open up pretty big. here is a youtube commercial