I think it depends on when and how it is done.
I was a big fan of Kane and Mark Henry both getting decent-length reigns as World Champions a few years back because I felt they deserved it at that point, in fact, it was long overdue and both talents delivered strong performances during their reigns. Unfortunately, Henry's was cut short due to his injury and probably because he didn't become champ until later in his career, but none the less, I enjoyed his run because he was presented as the tough, strong, almost indestructible monster that is his best persona.
I haven't been too much of a fan of Big Show's title wins in recent years. I think what hurt him in my eyes, and perhaps the eyes of other WWE fans is that during his earlier days in WWE, even though he did win the WWE title, he didn't hold it for that long and even after the Attitude Era he didn't hold the WWE or even the World title for a - pardon the pun - giant reign!
I think if Big Show had held the WWE or World title as long as say, JBL, held the WWE title on SmackDown all those years ago then Big Show would have more long standing legitimacy today. Not taking anything away from the man's talent or work ethic, both are excellent for a man his size! He still has value but he's been so flip floppy with his persona from face to heel and such that a late career title reign doesn't do much.
Actually, I think WWE missed the boat AGAIN with Big Show two years ago with the Andre the Giant Memorial Battle Royale at WrestleMania. The FIRST Battle Royale should have been the one Big Show won so he could say HE is the best giant in history and have something to back it up with. Then, he could go into a feud with Cesaro (who did win the first Battle Royal but it wasn't until this year that he really got a push) where Cesaro takes on the Big Show to prove he is a Giant Killer or something like that.
As for the current crop of probably soon-to-be retired WWE talent, I have some feelings about how I think they should end their careers. For Kane, I think he should come back one last time as the Demon Kane and feud with Rollins and then feud with Bray Wyatt and the Family as Bray Wyatt beats Kane and Kane JOINS the family but not like Daniel Bryan, Kane actually sees and believes in the ways of Wyatt and he joins the family for a while until Undertaker comes back at Royal Rumble and asks Kane to come back to his REAL (kayfabe) family and Undertaker and Kane (Brothers of Destruction) take on Harper & Rowan, the Wyatt Family, at WrestleMania.
For Big Show, I really don't care much at this point, I give him all the props he deserves and I know he is destined for the Hall of Fame but he really doesn't draw any interest from me in the ring with any angle I can imagine. Him against Ryback and Miz for the IC title should be okay and hopefully give Ryback that chance to show off his strength and then MAYBE use Big Show on Raw or SmackDown against Ryback for Ryback to win big a few more times as solidify himself as "The (New) Big Guy" but after that? I don't know. I really don't.
For Mark Henry, I've been a fan of his for a while and glad he got his World Title run and that PPV match and angle with Cena for the WWE title. I think since Henry is from Texas he should find a way to get on the WM card and face maybe a guy like Big E, who might be trying to break out again as a strongman heel, in a retirement match and let Big E get a very close pinfall win on Henry but then mock Henry after the match and allow Henry to do a final World's Strongest Slam on Big E to end his last match on a high note.
I think R-Truth may not get a built up final match. He might be like Christian, Rey Mysterio or Santion who didn't really get a well promoted final match. I think in those guys' cases it was because they were injured too much and their contract expired or was nearing expiry and instead of bringing them back WWE just let them go. That may happen for R-Truth and that's okay because he got a lot of nice things at the tail end of his career like a few years back he got a good angle and top match against Cena for the WWE title, he got a few Tag Title reigns and kept getting on PPV cards here and there.