I use mainly 1 gallon containers for both concentrate and diluted products. I purchase 1 gallon of distilled water and make one gallon of ready to use product with it. I have made a chart of all the correct amount of water to remove from the container and concentrate to add for all dilution ratios.
I usually do the dilution using one of 3 things: A mesuring cup for low dilution ratios (say 1:1 to about 1:10).
For medium dilution I use a graded turkey baster to transfer the correct amount of concentrated product.
For high dilution ratios I sometimes use a siringe.
In all cases or just about I use a funnel just to be on the safe side.
Some products cannot be dilluted this way because they will eat through the low grade plastic the distilled water comes in (Meg's super degreaser comes to mind). But for most products this works well.
To transfer to the 32 oz and 16 oz bottles I simply use a funnel.