At the time, I did watch both "Rich Man, Poor Man Book II" and "Executive Suite".
The first one continued the original miniseries´ story after the killing of Nick Nolte´s character. It kept most of the characters who (obviously) were alive at the end of RM PM, and added a few more, the next generation so to say, played by Gregg Henry and James Carroll Jordan (replacing Leigh McCloskey, who only appeared in a couple of episodes), aside from well-known names as
Maggie Gio..., I mean, Susan Sullivan as the lawyer to become new love interest for Peter Strauss´ character, called, you guess? Maggie!!
However, the female star of the first season, Susan Blakely, got the "I wanna be in the movies-itch" (but Nolte was the only one to really make it) and "asked to be axed" as soon as possible. She was RM PM´s Sue Ellen in the later episodes, so her exit was easy to manage...Her makeup was a bit OTT, by the way, because nobody knew at the time that you could be an alcoholic and look always glamorous...

The plot focused more and more on politics, and Strauss´ character truly became a Kennedy-esque figure, who was even more successful with women than the post-Pam Bobby...The ending of the series was quite a big hit in Spain and involved a fight between Senator Jordache (Strauss) and his one-eyed nemesis Falconetti...It didn´t end well for none of them, I guess that partly due to Strauss´ desire to avoid typecasting...and do movies, of course. I seem to remember that there was no real cliffhanger or loose end in the final episode, though there might have been a third season, at least for the number of storylines and characters...
I think that it paved the way for "Dallas" because continuity was usual in this second season and the writers kept the former characters coming in and out, as an attempt at giving more depth to the soapy storylines. Cain v. Abel (here they were actually cousins? stepbrothers?...), corruption of power, unwanted pregnancies, the usual things...
Funny trivia: "Dallas" isn´t the only soap with more than one "universe". Irwin Allen, author of the original novel RM PM was based on, hated the sequel so much that he wrote his own continuation, "Beggarman, Thief", which omitted all events from the second season and brought back a never-heard-of Jordache sister (played by Jean Simmons) who was in the movie business in the 60´s. It all sounded as typical Jackie Collins trash, though the rest of the cast was equally remarkable, like Glenn Ford, Lynn Redgrave and 2 pre-"Dynasty" stars: Bo Hopkins and Wayne Northrop. I´ve never seen this one...
"Executive Suite" was also aired in Catalonia by the same local station that had the decency to reprise "Dallas" after J.R.´s shooting (in 1984!!). It was at some point between daytime and primetime soaps. The acting was top-notch (some went on straight to "Dallas": Leigh McCloskey, William Skeleton Smithers, Stephen Elliott...and other actors with a soapy future like Ricardo Montalbán) and the writing had ambitions (interracial love, lesbianism, abortion...). As the title suggests, it adapted the Barbara Stanwyck movie and its book source, and if you had watched it AFTER the "Dallas" boom, you could say that it was just a rehash of its themes. But it wasn´t. In a way, a "Dallas" fan might see it as a prequel focused on WestStar Oil...
So this is it...However I think that the 70´s belonged to the literary miniseries and the cop shows. But every decade has a bit of every genre, and some shows are better than others, but become less successful and are quickly canceled. I would´ve loved watching more seasons of these two soaps from the 70´s.
PS: Miss Piggy and I would like to make a statement. We are NOT that old to remember this, we are just good at googling...