The unit I would recommend will really be determined by the frequencies that you want to look at.
The simpilest solution for voltage would be one of our units that can measure upto 20 volts this would save you having to use potential dividers.
The unit will also depend on accuracy that you are after and the resolution that you need.
Please look at these units that are available, if you can provide me with further details as specified above I will gladly assist in recommending a particular unit.
I woud recommend looking at the specification for the ADC212's and the ADC200's