For the first bottle, I would start off with a revolved part to get the outside shape. After the outside shape is defined, do an extrude cut thru the part to give a 'sharp' shape of the indents. then do a circular pattern of extrude cut to give you four instances of that cutout shape.
Fill the inside with a second revolve. Follow the inner revolve with a series of fillets, and I think you mostly have the shape you want for the first bottle.
The second bottle, I would start off with some lofts to get the basic shapes and then again break down the cutaways to get the final shape a little at a time.
I hope that helps.