My advice would be to see if you have some combination of unique fields that define what the entity is. If that's Date + OtherValue1, use that. Typical advice is look for something that satisfies range queries, though an identity can be used if you are looking at the insert/update/delete impact. Some advice here:

http://www.sqlskills.com/blogs/kimberly/the-clustered-index-debate-continues/

Note you haven't mentioned the PK, and I hope you have one. However, this doesn't need to be clustered, so your clustered index doesn't need to be unique.