Since some italics are simply not designed to be used as a regular typeface, don't use them that way! If you prefer the look of italics, make certain the italics look good as a body text (choose a Renaissance style) or you'll make the text harder to read. In this case, you should pick an appropriate set of caps; swash caps are appropriate so long as they aren't too flowery. Alternatively, a Renaissance roman uppercase with similar contrast might work.
It should almost go without saying, therefore, that you should ignore that I button in your word processor. Unless your word processor is smart enough to substitute fonts appropriately, you'll get a sheered roman which is even worse than an oblique - the axis will be incorrect as well as the width (and any number of other minor issues). Your kerning will be messed up and it just won't look right with letters squished together, running into each other.
Assuming you're using italics mixed with roman text, modern use of italics is fairly formal - italics are primarily a form of emphasis. Never use underlining. Underlining is what people used when they didn't have italics. Underlining told publishers to italicise the text. Underlining doesn't exist in typography. It doesn't matter what the APA or MLA handbook says, they are wrong in this case and generally are changing their position in recent versions.
The defined uses of italics are:
Titles - Magazines, plays, musical pieces, movies, TV shows, art, speechs, poems. An exception is that religious texts (the Bible, the Koran, the Everything FAQ) are not italicised. They just aren't.
Foreign words and phrases - Apparently they just have a je ne sais quoi that cries out for italics to increase their mystique.
Names of Planes, Trains, and Automobiles - Brand names are not italicised but actual names like Minnow, USS Nimitz, HMS Vanguard, Spirit of St. Louis, etc. Note that USS & HMS were not italicised. They aren't technically part of the name but are the item's title.
One important reminder: When using italics as above, do not place punctuation in italics unless it is part of the phrase. Therefore, "Did you read The Lord of the Rings?" is incorrect while "Where in the World is Carmen Sandiego? rocks!" is correct (even if completely false).
So you want to try...
As you may have inferred by this point, I like italics. Therefore, here are some attractive italic faces I suggest:
Centaur - Incorporates Monotype Arrighi for the italic with the Centaur roman.
Novarese - The only face I've seen that truely designs roman capitals with an italic lowerecase.
Fairfield - Modern typeface but the swash capitals give it a nice touch.
Poetica - One of my favorites if only because it's so complete - 4 chancery versions, roman caps, small caps, 4 sets of swash caps, old style figures, a whole set of ampersands and ligatures, swash initial and ending letters. Amazing.
Cochin - Playful, interesting italic. The w, h, s, and d stand out.
Cerigo - Subversive, subjugates the roman to the italic. Finally, revenge.
Remember the Dragnet-theme warning I suggested when it came to using exclamation points? (Quick recap: imagine that every time you use an exclamation point outside of dialogue, it comes accompanied by the first four notes of the Dragnet theme; you'll use them sparingly as a result.)
Well I've got a similar warning cue to employ when it comes to italics: imagine that whatever is italicized is being either whispered or Shouted Through A Bullhorn (however circumstances dictate); it's a matter of extremes, like it or not.
An italicized letter or quoted poem? A whisper.
A panicked warning (as in: "Look out!")? A shout through a bullhorn. (And bear in mind that when you combine italics with all caps -- "LOOK OUT!" -- it's overkill; the circumstances under which something like the above is italicized give the words or passage an immediacy that presenting them in all capital letters only diminishes; it's hitting the reader over the head with your intent: DEAR GOD, THIS IS REALLY, REALLY IMPORTANT AND I'M GOING TO MAKE DAMN SURE YOU KNOW IT!. Overkill. Don't do that.)
There is another -- and less directly acknowledged -- reason that it's a good idea to use italics sparingly: like it or not, a prolonged passage of italics quickly tires the eyes while reading. It's that simple.
As a writer, whenever I come to a passage that I know is going to have to be italicized (such as a letter or brief flashback), I apply the same rule to my own work that I do to anything that I might choose to read: no more than 3 pages. That is all that my eyes can take as a reader, so I assume that's my readers' limits, as well. After 3 pages, it just gets annoying; and the last thing you want is for a reader to become more aware of how you're presenting something than of its content.
So: a whisper or shouted through a bullhorn, no more than 3 pages, and you just might find that italics can be a useful ally, rather than the enemy.
So there we go, the interwebs prove Poi right. I shall no longer use italics for fluff. Just for general emphasis and other stuff such.