What criteria determines the size of the weight you select?

Couple of factors come to mind for me. First would be the amount of vegatation, second would be wind strength and third is current.

In most cases, I'm using the lightest weight I can get away with and still maintain a good feel of the bait.

I'll try to put these in order.

1) current (wind) - more current, more weight

2) water color - more visibility, less weight; super clear, no weight unless its a down rig

3) depth - more water, more weight

That's what I do.

Like stated above, i will use the lightest i can get away with. If i can wiggle a lure in some hyacinth mats with a 1/2oz instead of a 1oz i will. If there is no cover i will go weightless and use a SuperLine hook as the extra weight.

Wind, current, desired fall rate and vegetation. But always go try to go with the lightest unless fall rate is significant based on conditions.

    I use a weight just heavy enough so that I can keep in contact with the bottom.

Bill Dance taught many years ago.

Always use as light a weight, given the conditions, that allows you to maintain contact with the bait.  

I'll either be weightless or have a 1/8 ounce weight on the line. The only time I will put on a larger weight will be if the wind picks up or I start fishing deep water.

I start as light as possible but if I know that fish should be there and I'm not getting bit I will go heavier while varying the retrieve in order to see if they want something faster/more erratic.

Bill Dance taught many years ago.

Always use as light a weight, given the conditions, that allows you to maintain contact with the bait.

Yep, and if you are a river fisherman, it's all about current!

8-)

What about (ROF) rate of fall?

What about (ROF) rate of fall?

Catt, if you look at my post I refer to this. What I neglected to state is IMHO this is one of the most important consideration and should be taken into account when considering current, wind and vegetation. Can I have my GOLD STAR please.

Yea Leo you & I make 2

Yea Leo you & I make 2

This

if I know that fish should be there and I'm not getting bit I will go heavier

doesn't qualify?  I go heavier looking for a faster rate of fall or the ability to increase my retrieve speed while staying at a given depth.

You also didn't mention anything about changing trailer type/size/etc to effect ROF.