...but only grace and love are in the spotlight, does this amount to another gospel? I'm not talking about a single instance but rather a pattern that becomes evident over time. If the unpleasant topics related to the gospel--such as sin, hell, judgment, etc.--are rarely mentioned, and even then only briefly and in passing, whereas great attention is lavished on love, grace and mercy, what should be thought of that?

Such disproportion as you describe would be to deprive the context which magnifies Grace.

Agreed, Grace is most valued when we recognize the depth of our sin.
read j. Edwards, THE END TO WHICH GOD CREATED THE WORLD.

You lose sin, judgement, wrath, hell, etc.---you lose the gospel, plain and simple. It seems that preachers who do not shy away from these "uncomfortable" doctrines are not usually found preaching in mega-churches.

I certainly think that such an omission amounts to a different gospel (which is no gospel), but it's also the false gospel most common now, in this country at least. It's the particular distortion that fits most comfortably with the modern religion of tolerance. No sin, no judgement, - to get into Heaven, all you have to do is die.

If just the kettle drum and the cymbals are played, how will anyone recognize the symphony?

It even appears as if grace has in this day and age been redefined as "tolerance". That's the new gospel then---the gospel of tolerance, which has nothing to do with God's attributes (save some vague, beneficent love for all mankind). That's why many are seeking a "grace-oriented church" where everyone is nice and sin is never confronted, much less even mentioned.