"Where on this lake would you need 200' of anchor line? Since you're specifying proper equipment for viewing fireworks at night do you have a preference on anchor weight and line size as well? And are you sure one is enough? (a throwback to “Stormy Weather” thread)"
I'm not feeling the "love" in your remarks Winni Diver. You almost sound to be sarcastic.
I am used to anchoring in Long Island Sound where 200' does come in handy at times. But as another poster said, about 30 vertical feet from deck to bottom at a 7 to 1 ratio. Or 3 to 1 in 60'.
But if you'd rather anchor using 25' of clothesline and a cinder block, that's also an option. What I enjoy is when I see a boater in 25' of water using a 15' bow line tied to the anchor. I also have seen an anchor get thrown over the side and all the liine go with it, due to the fact that the bitter end wasn't tied off to the boat.
And since I see the majority of people carrying and "using" a second anchor at the sand bars; then "yes", I do suggest he carry a second anchor. "Weight dependent upon the size of his vessel.

Let's see, all my years diving I have never needed my seccond, i.e. back up regulator, does that mean I don't need it?
Gwood, the fireworks are at 10 pm and they last about 20 minutes.Might I suggest boating to Liliakalanni's (or however it's spelled) for ice cream and then boat to the docks at Weirs and walkaround, then go out and see the fireworks, watch them from your boat tied to the dock if you feel more comfortable.
I suggest you get familiar with your gps during daylight trips so that you'll be comfortable using it that night. If you have it on during your trip down lake to Weirs then using the map page you will have a "line" to follow on your return home.
Try to use your floodlight minimally as that ruins your night vision and annoys the heck out of your fellow boaters. (Not that the fireworks will help your night vision. Wearing a welder's helmet during the show will help with that.

)
On a moon filled night, you'll have great ambient light.
Have fun.
CZ