Here is a summary of U.S. coin and bullion values based on sample spot prices of silver. 

Things to Consider:

Lingo:
Often times dealers will offer to buy or sell your coins at a certain amount X face value.  For example, if silver was trading at $25 an ounce, a dime would be worth  $1.81, or 18 X face value. 

Pricing:
There are many honest coin dealers, but there are more that are looking to take advantage of unsuspecting coin sellers.  As a general rule, selling your junk silver coins anywhere from 10-15% below their silver value is a good deal.  When purchasing from a dealer, I would recommend against paying higher than 10% above the silver weight.

Silver Dollars:
Silver dollars deserve special consideration.  If you are considering selling silver dollars, it is important to shop around.  I would recommend trying to find a buyer who will pay around spot price for them (or 5% below for Peace dollars).  For reference, dealers will sell BULK amounts of Morgan silver dollars for 10-15% above the spot price.  Individual coins sell for higher, and common date Morgans in exceptional condition can go for 20-25% above the spot price.

Before selling your coins for their silver value, double check to make sure they are not a rare date coin.  Rare date coins can often sell for much higher than their silver content.

Silver @ $25 Spot Price

Morgan Silver Dollar: $19.34
Peace Dollar: $19.34
90% Half Dollar: $9.04
90% Quarter: $4.52
90% Dimes: $1.81
40% Half Dollar: $3.70

Silver @ $30 Spot Price

Morgan Silver Dollar: $23.20
Peace Dollar: $23.20
90% Half Dollar: $10.85
90% Quarter: $5.43
90% Dimes: $2.17
40% Half Dollar: $4.44

Silver @ $35 Spot Value

Morgan Silver Dollar: $27.07
Peace Dollar: $27.07
90% Half Dollar: $12.66
90% Quarter: $6.34
90% Dimes: $2.53
40% Half Dollar: $5.18

Silver @ $40 Spot Value

Morgan Silver Dollar: $30.94
Peace Dollar: $30.94
90% Half Dollar: $14.47
90% Quarter: $7.24
90% Dimes: $2.89
40% Half Dollar: $5.92

Silver @ $45 Spot Value

Morgan Silver Dollar: $34.80
Peace Dollar: $34.80
90% Half Dollar: $16.28
90% Quarter: $8.14
90% Dimes: $3.26
40% Half Dollar: $6.67

Silver @ $50 Spot Value

Morgan Silver Dollar: $38.67
Peace Dollar: $38.67
90% Half Dollar: $18.08
90% Quarter: $9.04
90% Dimes: $3.62
40% Half Dollar: $7.40