Making sell decisions: taking profits vs capital gains taxes?

We've never really sold anything--ultimate buy and hold people--so we're not used to making sell decisions.

I'm retired (but my wife isn't yet) and I've started to think about spending models and taxes and leaving the large capital gains to our kids. (Basis step-ups rule!) We're almost at the point where we could live off SS and income streams without selling anything with capital gains.

Our preference is low cost index funds. One exception is some Ciena stock (because my wife worked there for a time) and it has really rocketed up recently. Suddenly it's 7 or 8% of our portfolio.

Regarding our Ciena stock holding

1. It has large capital gains (that our heirs could avoid paying taxes on).
2. I worry that the recent prices won't be sustained and selling now could be better than avoiding the cap gains taxes. But what do I know?
3. We don't need the cash. We'd probably buy more low cost index funds.
4. Single stocks aren't our style. We prefer diversification.
5. We're 62 and 60.

Thoughts? Sell or hold?